feat: add version getter to VersionedTransaction class

[jstarry]

Problem

When differentiating between VersionedTransaction and Transaction, it's a little awkward to use if ('message' in transaction'). It'd be more natural to check for the existence of a version property.

Summary of Changes

Expose VersionedTransaction.message.version with a new version getter function

Fixes #

[codecov]

Codecov Report

Merging #27734 (08e3e1f) into master (e779032) will increase coverage by 0.4%.
The diff coverage is n/a.

@@            Coverage Diff            @@
##           master   #27734     +/-   ##
=========================================
+ Coverage    76.9%    77.3%   +0.4%     
=========================================
  Files          48       55      +7     
  Lines        2505     2889    +384     
  Branches      355      402     +47     
=========================================
+ Hits         1927     2234    +307     
- Misses        448      514     +66     
- Partials      130      141     +11     

[mergify]

automerge label removed due to a CI failure