Add aarch64 (Arm 64-bit) CI job

[tautschnig]

Run regression tests and build release package using GitHub's newly (publicly) available aarch64 runner.

• 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

Attention: Patch coverage is 57.31707% with 35 lines in your changes missing coverage. Please review.

Project coverage is 80.36%. Comparing base (3c915eb) to head (4328cb0).

Files with missing lines	Patch %	Lines
src/util/simplify_expr.cpp	39.39%	20 Missing ⚠️
src/cpp/cpp_internal_additions.cpp	27.27%	8 Missing ⚠️
src/ansi-c/goto-conversion/builtin_functions.cpp	80.00%	4 Missing ⚠️
src/ansi-c/c_typecheck_expr.cpp	57.14%	3 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #8572      +/-   ##
===========================================
- Coverage    80.37%   80.36%   -0.01%     
===========================================
  Files         1686     1686              
  Lines       206885   206956      +71     
  Branches        73       73              
===========================================
+ Hits        166276   166317      +41     
- Misses       40609    40639      +30     

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