bulk volunteer deactivation page

[struan]

enables deactivating all existing non staff and superuser volunteers who are assigned to a particular stage for a session

Fixes #136

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 98.61111% with 1 line in your changes missing coverage. Please review.

Project coverage is 81.39%. Comparing base (f9f76a8) to head (bba8736).
Report is 32 commits behind head on main.

Files with missing lines	Patch %	Lines
crowdsourcer/views/volunteers.py	93.33%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #186      +/-   ##
==========================================
+ Coverage   80.84%   81.39%   +0.54%     
==========================================
  Files          88       92       +4     
  Lines        4449     5316     +867     
  Branches      391      495     +104     
==========================================
+ Hits         3597     4327     +730     
- Misses        766      865      +99     
- Partials       86      124      +38     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.