Restore coverage tracking

[elia]

Summary

At some point a few months ago it stopped working.

Merge the coverage command and job and avoid env variables that seem to not work properly and bump the ruby version.

Checklist

Check out our PR guidelines for more details.

The following are mandatory for all PRs:

• I have written a thorough PR description.
• I have kept my commits small and atomic.
• I have used clear, explanatory commit messages.

The following are not always needed:

• 📖 I have updated the README to account for my changes.
• 📑 I have documented new code with YARD.
• 🛣️ I have opened a PR to update the guides.
• ✅ I have added automated tests to cover my changes.
• 📸 I have attached screenshots to demo visual changes.

[codecov]

Codecov Report

Attention: 206 lines in your changes are missing coverage. Please review.

Comparison is base (9413383) 88.46% compared to head (4465f02) 88.66%.
Report is 267 commits behind head on main.

Files	Patch %	Lines
admin/lib/solidus_admin/install_tailwindcss.rb	0.00%	72 Missing ⚠️
...ib/generators/solidus/install/install_generator.rb	19.04%	17 Missing ⚠️
...erators/solidus_admin/install/install_generator.rb	0.00%	11 Missing ⚠️
admin/lib/solidus_admin/configuration.rb	72.00%	7 Missing ⚠️
...s/spree/payment_method/simple_bogus_credit_card.rb	33.33%	6 Missing ⚠️
...ntrollers/solidus_admin/option_types_controller.rb	77.27%	5 Missing ⚠️
...ollers/solidus_admin/payment_methods_controller.rb	81.48%	5 Missing ⚠️
...controllers/solidus_admin/taxonomies_controller.rb	77.27%	5 Missing ⚠️
.../controllers/solidus_admin/addresses_controller.rb	57.14%	3 Missing ⚠️
...ers/solidus_admin/adjustment_reasons_controller.rb	84.21%	3 Missing ⚠️
... and 39 more

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #5580      +/-   ##
==========================================
+ Coverage   88.46%   88.66%   +0.20%     
==========================================
  Files         633      683      +50     
  Lines       15160    16299    +1139     
==========================================
+ Hits        13411    14452    +1041     
- Misses       1749     1847      +98     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.