Log pdflatex output on error

[praseodym]

Changes

Log stdout and stderr when pdflatex exits with a non-zero return code.

Issue ticket number and link

n/a

Proof

[2023-04-05 09:57:24 +0000] [8] [INFO] [keiko] [keiko.keiko] pdflatex [run=0] [report_id=8d5fb95b] [template=bevindingenrapport] [command=pdflatex -synctex=1 -interaction=nonstopmode 8d5fb95b.keiko.tex]
[2023-04-05 09:57:24 +0000] [8] [ERROR] [keiko] [keiko.keiko] This is pdfTeX, Version 3.14159265-2.6-1.40.21 (TeX Live 2020/Debian) (preloaded format=pdflatex)
 restricted \write18 enabled.
[..]
Exception: ('Error in pdflatex run %d', 0)

Extra instructions for others

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• All the commits in this PR are properly PGP-signed and verified;
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• This PR is "bite-sized" and only focuses on a single issue, problem, or feature;
• I am not reinventing the wheel: there is no high-quality library that already has this feature;
• I have changed the example .env files if I added, removed, or changed any config options, and I have informed others that they need to modify their .env files if required;
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[ammar92]

Nice. Just minimal remarks to improve it even more (subjective)

[praseodym]

Backport to 1.7 in #669