Fix filename completion in bash autocompletion

[tautschnig]

Bash globbing does not support | for alternatives, which meant that the prior pattern would only match file names that contained a |.

• 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.
• n/a 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 78.71%. Comparing base (66004dc) to head (7541547).

Additional details and impacted files

@@           Coverage Diff            @@
##           develop    #8587   +/-   ##
========================================
  Coverage    78.71%   78.71%           
========================================
  Files         1732     1732           
  Lines       199536   199536           
  Branches     18281    18245   -36     
========================================
  Hits        157057   157057           
  Misses       42479    42479           

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