Add a missing update step to renew software sources in apt lists

[NlightNFotis]

• Each commit message has a non-empty body, explaining why the change was made.
• 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).
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[codecov]

Codecov Report

Merging #6738 (c3b3797) into develop (1a70e34) will decrease coverage by 0.00%.
The diff coverage is n/a.

@@             Coverage Diff             @@
##           develop    #6738      +/-   ##
===========================================
- Coverage    76.86%   76.86%   -0.01%     
===========================================
  Files         1589     1589              
  Lines       183813   183813              
===========================================
- Hits        141290   141289       -1     
- Misses       42523    42524       +1     

Impacted Files	Coverage Δ
src/util/piped_process.cpp	81.92% <0.00%> (-1.21%)	⬇️

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