Feat(): Enable async workers for flask and django

[alithethird]

Applicable spec:

Overview

Rationale

Juju Events Changes

Module Changes

Library Changes

Checklist

• The charm style guide was applied
• The contributing guide was applied
• The changes are compliant with ISD054 - Managing Charm Complexity
• The documentation is generated using src-docs
• The documentation for charmhub is updated
• The PR is tagged with appropriate label (urgent, trivial, complex)

[cbartz]

Partial review from mobile phone

[javierdelapuente]

nice! a few comments

[github-actions]

license-eye has checked 220 files.

Valid	Invalid	Ignored	Fixed
147	1	72	0

Click to see the invalid file list

• examples/flask/flask-async.rst

Use this command to fix any missing license headers

```bash

docker run -it --rm -v $(pwd):/github/workspace apache/skywalking-eyes header fix

</details>

[github-actions]

Test coverage for 88d898f

Name                                          Stmts   Miss Branch BrPart  Cover   Missing
-----------------------------------------------------------------------------------------
src/paas_app_charmer/__init__.py                  2      0      0      0   100%
src/paas_app_charmer/django/__init__.py           2      0      0      0   100%
src/paas_app_charmer/django/charm.py              2      0      0      0   100%
src/paas_app_charmer/fastapi/__init__.py          2      0      0      0   100%
src/paas_app_charmer/fastapi/charm.py             2      0      0      0   100%
src/paas_app_charmer/flask/__init__.py            2      0      0      0   100%
src/paas_app_charmer/flask/charm.py               2      0      0      0   100%
src/paas_app_charmer/go/__init__.py               2      0      0      0   100%
src/paas_app_charmer/go/charm.py                  2      0      0      0   100%
src/paas_charm/__init__.py                       32     17      0      0    47%   13-14, 19-20, 26-27, 33-37, 43-44, 50-51, 57-58
src/paas_charm/_gunicorn/__init__.py              0      0      0      0   100%
src/paas_charm/_gunicorn/charm.py                42      0      6      0   100%
src/paas_charm/_gunicorn/webserver.py            91      4     16      1    95%   207, 219-225
src/paas_charm/_gunicorn/workload_config.py       8      0      0      0   100%
src/paas_charm/_gunicorn/wsgi_app.py             21      0      2      0   100%
src/paas_charm/app.py                           166      0     56      3    99%   113->exit, 170->176, 358->360
src/paas_charm/charm.py                         242     23     54      3    91%   34-35, 42-43, 205, 215-216, 218-219, 248-252, 379-380, 385, 390, 395, 405, 410, 415, 420, 425, 450
src/paas_charm/charm_state.py                   107      2     12      2    97%   187, 277
src/paas_charm/charm_utils.py                    23      0      0      0   100%
src/paas_charm/database_migration.py             35      0      2      0   100%
src/paas_charm/databases.py                      25      2      6      1    90%   89-90
src/paas_charm/django/__init__.py                 2      0      0      0   100%
src/paas_charm/django/charm.py                   50      4      8      2    90%   49, 124, 139-140
src/paas_charm/exceptions.py                      5      0      0      0   100%
src/paas_charm/fastapi/__init__.py                2      0      0      0   100%
src/paas_charm/fastapi/charm.py                  31      0      0      0   100%
src/paas_charm/flask/__init__.py                  2      0      0      0   100%
src/paas_charm/flask/charm.py                    26      0      0      0   100%
src/paas_charm/framework.py                      23      4     12      2    77%   36, 49-51
src/paas_charm/go/__init__.py                     2      0      0      0   100%
src/paas_charm/go/charm.py                       28      0      0      0   100%
src/paas_charm/observability.py                  24      3      4      1    86%   42->46, 73-77
src/paas_charm/rabbitmq.py                       78      2     22      5    93%   117->exit, 122->exit, 157->exit, 159-160, 181->175
src/paas_charm/secret_storage.py                 50      2     14      4    91%   55->54, 56->58, 86, 105
src/paas_charm/utils.py                          44      7     14      5    79%   34, 36, 56-57, 75, 79, 104
-----------------------------------------------------------------------------------------
TOTAL                                          1177     70    228     29    93%

Static code analysis report

Run started:2024-12-13 03:43:13.740094

Test results:
  No issues identified.

Code scanned:
  Total lines of code: 2476
  Total lines skipped (#nosec): 1
  Total potential issues skipped due to specifically being disabled (e.g., #nosec BXXX): 2

Run metrics:
  Total issues (by severity):
  	Undefined: 0
  	Low: 0
  	Medium: 0
  	High: 0
  Total issues (by confidence):
  	Undefined: 0
  	Low: 0
  	Medium: 0
  	High: 0
Files skipped (0):