[Snyk] Security upgrade alpine from 3.16 to 3

[snyk-bot]

Keeping your Docker base image up-to-date means you’ll benefit from security fixes in the latest version of your chosen image.

Changes included in this PR

• Dockerfile

We recommend upgrading to alpine:3, as this image has only 0 known vulnerabilities. To do this, merge this pull request, then verify your application still works as expected.

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[codecov]

Codecov Report

Merging #106 (ed0d9d2) into master (0638a9e) will increase coverage by 1.16%.
The diff coverage is n/a.

❗ Current head ed0d9d2 differs from pull request most recent head 407c8aa. Consider uploading reports for the commit 407c8aa to get more accurate results

@@            Coverage Diff             @@
##           master     #106      +/-   ##
==========================================
+ Coverage   68.50%   69.67%   +1.16%     
==========================================
  Files          31       31              
  Lines        1667     1385     -282     
==========================================
- Hits         1142      965     -177     
+ Misses        447      342     -105     
  Partials       78       78              

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see 28 files with indirect coverage changes