fix: Add history line when changing the review deadline. (fixes #6598)

[kivinen]

Add history line when the review deadline is changed. Also fixes the subject line of the email sent out, so if there is no specific revision requested it does not print the extra "-" at the end.

Subject used to look:

Subject: Deadline changed: Secdir last call review of draft-ietf-opsawg-9092-update-

now it will look:

Subject: Deadline changed: Secdir last call review of draft-ietf-opsawg-9092-update

[codecov]

Codecov Report

Attention: Patch coverage is 80.00000% with 1 lines in your changes are missing coverage. Please review.

Project coverage is 88.94%. Comparing base (187c2c5) to head (7a15257).
Report is 59 commits behind head on main.

Files	Patch %	Lines
ietf/doc/views_review.py	80.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #7194      +/-   ##
==========================================
- Coverage   88.98%   88.94%   -0.05%     
==========================================
  Files         291      291              
  Lines       40717    41067     +350     
==========================================
+ Hits        36233    36526     +293     
- Misses       4484     4541      +57     

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