Fix email regex

[0xAda]

This was removed for some reason in #73

[codecov]

Codecov Report

Merging #234 (745a52d) into master (35b9f20) will increase coverage by 0.01%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #234      +/-   ##
==========================================
+ Coverage   94.40%   94.41%   +0.01%     
==========================================
  Files         107      107              
  Lines        4754     4767      +13     
  Branches      272      272              
==========================================
+ Hits         4488     4501      +13     
  Misses        223      223              
  Partials       43       43              

Impacted Files	Coverage Δ
src/authentication/providers.py	100.00% <100.00%> (ø)
src/authentication/tests.py	100.00% <100.00%> (ø)

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