Remove date range for LICENSE

[philipphofmann]

While updating the date ranges for multiple PRs, Michi pointed out that we don't need date ranges for our licenses. I'm sorry about the fuzz.

In our internal Open Source Legal Policy, we decided that licenses don't require a data range. This also has the advantage of not updating the date range yearly.

#skip-changelog

cc @gavin-zee

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 80.16%. Comparing base (7c757c2) to head (1eeacfb).
Report is 2 commits behind head on master.

✅ All tests successful. No failed tests found.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #3991      +/-   ##
==========================================
- Coverage   80.21%   80.16%   -0.06%     
==========================================
  Files         139      139              
  Lines       15394    15394              
  Branches     2596     2596              
==========================================
- Hits        12349    12341       -8     
- Misses       2202     2209       +7     
- Partials      843      844       +1     

see 3 files with indirect coverage changes