CI: fix docker build

3 jobs for master in 68 minutes and 8 seconds (queued for 1 second)
Status Job ID Name Coverage
  Test
failed job_clang_amd64 #5016
amd64

01:08:07

passed job_clang_cxx_amd64 #5017
amd64

00:34:09

failed job_gcc_amd64 #5015
amd64

00:55:29

 
Name Stage Failure
failed
job_gcc_amd64 Test
build succeeded, 112 warnings.

Testing of doctests in the sources finished, look at the results in builds/generation.rst/output.txt.
<doctest default (setup code)[0]>:39: MatplotlibDeprecationWarning: Support for setting the 'text.latex.preamble' or 'pgf.preamble' rcParam to a list of strings is deprecated since 3.3 and will be removed two minor releases later; set it to a single string instead.
rcParams["text.latex.preamble"] = [#r"\usepackage{times}",
<doctest condensation_graph (setup code)[0]>:39: MatplotlibDeprecationWarning: Support for setting the 'text.latex.preamble' or 'pgf.preamble' rcParam to a list of strings is deprecated since 3.3 and will be removed two minor releases later; set it to a single string instead.
rcParams["text.latex.preamble"] = [#r"\usepackage{times}",
Cleaning up file based variables
ERROR: Job failed: exit status 1
failed
job_clang_amd64 Test
build succeeded, 112 warnings.

Testing of doctests in the sources finished, look at the results in builds/generation.rst/output.txt.
<doctest default (setup code)[0]>:39: MatplotlibDeprecationWarning: Support for setting the 'text.latex.preamble' or 'pgf.preamble' rcParam to a list of strings is deprecated since 3.3 and will be removed two minor releases later; set it to a single string instead.
rcParams["text.latex.preamble"] = [#r"\usepackage{times}",
<doctest condensation_graph (setup code)[0]>:39: MatplotlibDeprecationWarning: Support for setting the 'text.latex.preamble' or 'pgf.preamble' rcParam to a list of strings is deprecated since 3.3 and will be removed two minor releases later; set it to a single string instead.
rcParams["text.latex.preamble"] = [#r"\usepackage{times}",
Cleaning up file based variables
ERROR: Job failed: exit status 1