feat: add handler type for photo captions

[davidramiro]

With incoming messages that come with a photo, HandlerTypeMessageText does not catch those as they are within Update.Message.Caption and not Text.

I initially thought about adding a check for Caption if Text is empty in the HandlerTypeMessageText case, but I think a separate type is cleaner. Let me know what you think!

[codecov-commenter]

⚠️ Please install the to ensure uploads and comments are reliably processed by Codecov.

Codecov Report

Attention: Patch coverage is 33.33333% with 4 lines in your changes missing coverage. Please review.

Project coverage is 49.85%. Comparing base (dda4073) to head (1e46f61).

Files with missing lines	Patch %	Lines
options.go	0.00%	4 Missing ⚠️

❗ Your organization needs to install the Codecov GitHub app to enable full functionality.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #138      +/-   ##
==========================================
- Coverage   49.90%   49.85%   -0.05%     
==========================================
  Files          26       26              
  Lines        2090     2096       +6     
==========================================
+ Hits         1043     1045       +2     
- Misses       1003     1007       +4     
  Partials       44       44              

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