feat: Allow additional redis args

[aquamatthias]

Hi,

we use arq in https://github.com/someengineering/fixbackend - thanks for a great library.
We are missing an option to provide redis settings unavailable in arq RedisSettings.
One example would be: health_check_interval.

This PR would allow the arguments to be passed when the pool is created.

[codecov]

Codecov Report

Merging #445 (cab6f1e) into main (94cd878) will increase coverage by 0.19%.
Report is 10 commits behind head on main.
The diff coverage is n/a.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #445      +/-   ##
==========================================
+ Coverage   96.27%   96.47%   +0.19%     
==========================================
  Files          11       11              
  Lines        1074     1078       +4     
  Branches      209      190      -19     
==========================================
+ Hits         1034     1040       +6     
  Misses         19       19              
+ Partials       21       19       -2     

Files	Coverage Δ
arq/connections.py	89.93% <ø> (-0.13%)	⬇️

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