fix: tmclient update header validation for v0.44.x

[rnbguy]

Closes: #911 but on v0.44.x release

Description

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PR author checklist:

• Added changelog entry, using unclog.
• Added tests.
• Linked to GitHub issue.
• Updated code comments and documentation (e.g., docs/).
• Tagged one reviewer who will be the one responsible for shepherding this PR.

Reviewer checklist:

• Reviewed Files changed in the GitHub PR explorer.
• Manually tested (in case integration/unit/mock tests are absent).

[codecov]

Codecov Report

Attention: 8 lines in your changes are missing coverage. Please review.

Comparison is base (5a79491) 71.49% compared to head (f87ef0a) 71.65%.

Additional details and impacted files

@@                 Coverage Diff                 @@
##           release/v0.44.x     #917      +/-   ##
===================================================
+ Coverage            71.49%   71.65%   +0.15%     
===================================================
  Files                  124      124              
  Lines                14960    15035      +75     
===================================================
+ Hits                 10696    10773      +77     
+ Misses                4264     4262       -2     

Files	Coverage Δ
crates/ibc/src/clients/ics07_tendermint/header.rs	72.68% <ø> (+1.11%)	⬆️
...ibc/src/core/ics02_client/handler/update_client.rs	95.49% <100.00%> (+0.04%)	⬆️
...ates/ibc/src/core/ics04_channel/acknowledgement.rs	78.51% <ø> (ø)
crates/ibc/src/mock/context.rs	75.44% <92.98%> (+0.88%)	⬆️
crates/ibc/src/mock/host.rs	91.72% <86.20%> (-1.54%)	⬇️

... and 1 file with indirect coverage changes

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[Farhad-Shabani]

Thanks for taking care of this @rnbguy!