Release CBMC 6.7.1

[tautschnig]

This release addresses bugs in our handling of array-update ("with") expressions (via #8674) and gaps in our C17/C23 support (via #8673).

• Each commit message has a non-empty body, explaining why the change was made.
• n/a Methods or procedures I have added are documented, following the guidelines provided in CODING_STANDARD.md.
• The feature or user visible behaviour I have added or modified has been documented in the User Guide in doc/cprover-manual/
• Regression or unit tests are included, or existing tests cover the modified code (in this case I have detailed which ones those are in the commit message).
• n/a My commit message includes data points confirming performance improvements (if claimed).
• My PR is restricted to a single feature or bugfix.
• n/a White-space or formatting changes outside the feature-related changed lines are in commits of their own.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 80.39%. Comparing base (ea7b092) to head (b9ee6ec).
Report is 2 commits behind head on develop.

Additional details and impacted files

@@ Coverage Diff @@## develop #8677 +/- ##
===========================================
- Coverage 80.39% 80.39% -0.01% 
===========================================
Files 1688 1688 Lines 207392 207392 Branches 73 73 ===========================================
- Hits 166742 166739 -3 - Misses 40650 40653 +3 

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