ci: add docker arm64 image

[mgrachev]

✔ Checklist:

• Commit messages have been written in Conventional Commits format;
• This PR has been added to CHANGELOG.md (at the top of the list);
• Tests for the changes have been added (for bug fixes / features);
• Docs have been added / updated on the dotenv-linter.github.io (for bug fixes / features).

[codecov-commenter]

Codecov Report

Merging #533 (c4cce2d) into master (3fd096e) will decrease coverage by 0.00%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master     #533      +/-   ##
==========================================
- Coverage   98.94%   98.94%   -0.01%     
==========================================
  Files          43       43              
  Lines        2759     2750       -9     
==========================================
- Hits         2730     2721       -9     
  Misses         29       29              

Impacted Files	Coverage Δ
src/fs_utils.rs	95.34% <0.00%> (-0.06%)	⬇️
src/lib.rs	98.98% <0.00%> (-0.02%)	⬇️
src/common/comment.rs	100.00% <0.00%> (ø)
src/common/line_entry.rs	100.00% <0.00%> (ø)
src/fixes/unordered_key.rs	100.00% <0.00%> (ø)

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[mstruebing]

🎉