pinned ubuntu version to resolve failing gha jobs until support avail…

[azaidi06]

…ble in idaes extension

Fixes

issue #1499
#1499

Summary/Motivation:

Widespread test failures with Ubuntu 24.04, including ubuntu-latest GHA runner image -- this won't work without a pinned version of Ubuntu -- the longer term fix will take a while as it requires updated binaries of IDAES

Changes proposed in this PR:

Update the core.yml file to specify GHA is pinned to Ubuntu 22.04

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[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 76.98%. Comparing base (2515fe8) to head (45b5408).
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1506      +/-   ##
==========================================
- Coverage   76.98%   76.98%   -0.01%     
==========================================
  Files         382      382              
  Lines       61911    61911              
  Branches    10126    10126              
==========================================
- Hits        47663    47660       -3     
- Misses      11848    11852       +4     
+ Partials     2400     2399       -1     

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