CI: add python3-dev to installed packages

2 jobs for master in 1 minute and 12 seconds (queued for 2 seconds)
Name Stage Failure
fetch-and-build Fetch And Build
       11 | #include <limits.h>
| ^~~~~~~~~~
compilation terminated.
error: command 'gcc' failed with exit status 1
ERROR: Command errored out with exit status 1: /usr/bin/python3.8 -u -c 'import sys, setuptools, tokenize; sys.argv[0] = '"'"'/tmp/pip-install-6fcf7hfi/regex/'"'"'; __file__='"'"'/tmp/pip-install-6fcf7hfi/regex/'"'"';f=getattr(tokenize, '"'"'open'"'"', open)(__file__);'"'"'\r\n'"'"', '"'"'\n'"'"');f.close();exec(compile(code, __file__, '"'"'exec'"'"'))' install --record /tmp/pip-record-_o1d4pb4/install-record.txt --single-version-externally-managed --compile Check the logs for full command output.
WARNING: You are using pip version 19.2.3, however version 20.1 is available.
You should consider upgrading via the 'pip install --upgrade pip' command.
ERROR: Job failed: exit code 1