[teams] Add tests

[ricoberger]

• I added a CHANGELOG entry for this change.
• I adjusted the corresponding documentation for this change.
• I adjusted the values.yaml file and the documentation for all values.

[codecov-commenter]

Codecov Report

Merging #268 (08e7f50) into main (8e9cabc) will increase coverage by 0.44%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##             main     #268      +/-   ##
==========================================
+ Coverage   34.54%   34.99%   +0.44%     
==========================================
  Files          90       90              
  Lines        7613     7613              
==========================================
+ Hits         2630     2664      +34     
+ Misses       4947     4913      -34     
  Partials       36       36              

Impacted Files	Coverage Δ
plugins/teams/teams.go	100.00% <ø> (+64.15%)	⬆️

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