Add GitHub registry upload

[Teddy-1000]

Add CI to run on merge to main branch. Will build and upload to the github registry.

[github-actions]

API Unit Test Coverage Report

File	Stmts	Miss	Cover	Missing
\_\_init\_\_.py	0	0	100%
datastore_pb2.py	60	48	20%	24–71
datastore_pb2_grpc.py	43	23	47%	37–52, 85–87, 92–94, 99–101, 106–108, 112–136, 174, 191, 208, 225
grpc_getter.py	20	11	45%	15–16, 20–23, 27–29, 33–35
locustfile.py	15	15	0%	1–31
main.py	34	5	85%	41, 51–52, 62–63
metadata_endpoints.py	55	25	55%	42–51, 55, 72–151, 155
response_classes.py	5	0	100%
utilities.py	77	19	75%	15, 33, 40, 62–65, 73–80, 85–92, 112, 116, 118
custom_geo_json
edr_feature_collection.py	6	0	100%
formatters
\_\_init\_\_.py	11	0	100%
covjson.py	53	1	98%	75
geojson.py	15	2	87%	17, 42
routers
\_\_init\_\_.py	0	0	100%
edr.py	100	7	93%	119, 131, 139, 241–242, 297–298
feature.py	46	19	59%	75–108, 124–129, 135–157
TOTAL	540	175	68%

API Unit Test Coverage Summary

Tests	Skipped	Failures	Errors	Time
23	0 💤	0 ❌	0 🔥	2.067s ⏱️

[lukas-phaf]

One comment added, and I wonder why not also do it for branches, as these can be useful for testing also.

Approved, so we can see if it works.