Remove unused variable from #1018

[tupaschoal]

• Fixes a lint issue introduced on Adapting calendar to use a non-remote environment #1018 which started breaking the CI after Checking lint in PR CI checks #1023.
• Amend changelog with missing fix from Fix #1008: Sourced conflicting holidays being imported by default #1011

[codecov]

Codecov Report

Merging #1030 (454de30) into main (3f7076e) will increase coverage by 4.34%.
Report is 3 commits behind head on main.
The diff coverage is 17.94%.

@@            Coverage Diff             @@
##             main    #1030      +/-   ##
==========================================
+ Coverage   75.02%   79.37%   +4.34%     
==========================================
  Files          26       21       -5     
  Lines        2202     1275     -927     
  Branches      346      189     -157     
==========================================
- Hits         1652     1012     -640     
+ Misses        550      263     -287     

Files	Coverage Δ
js/time-balance.js	100.00% <ø> (ø)
js/main-window.js	73.50% <87.50%> (+0.46%)	⬆️
js/menus.js	81.73% <0.00%> (ø)
src/calendar.js	0.00% <0.00%> (ø)

... and 4 files with indirect coverage changes