fix: show meeting timezone when editing sessions

[rjsparks]

Fixes #5353

[codecov]

Codecov Report

Merging #5619 (591a429) into main (6089d47) will decrease coverage by 0.02%.
The diff coverage is 76.74%.

@@            Coverage Diff             @@
##             main    #5619      +/-   ##
==========================================
- Coverage   88.75%   88.73%   -0.02%     
==========================================
  Files         285      285              
  Lines       39810    39838      +28     
==========================================
+ Hits        35333    35350      +17     
- Misses       4477     4488      +11     

Impacted Files	Coverage Δ
ietf/doc/views_doc.py	91.61% <62.50%> (-0.04%)	⬇️
ietf/meeting/templatetags/session_filters.py	87.50% <85.18%> (-4.17%)	⬇️

... and 3 files with indirect coverage changes

[jennifer-richards]

This should work, though it'll print the timezone as "PST8PDT" or "America/Halifax" rather than a more typical brief description like "PDT" or "ADT". I don't think that's a problem, just pointing it out in case you happened to test with UTC where it might not have been obvious.