Update ts-graphviz/setup-graphviz v1.1 → v1.2.0

[khaeru]

Addresses CI failures:

1. Third-party action ts-graphviz/setup-graphviz fails on macOS only in the "brew update" step since ~2022-12-22.
   • Update the action version
   • Use the new option macos-skip-brew-update provided to avoid such issues.
2. test_R_transport*() (run Jupyter R notebooks) times out on ubuntu-latest only, since at least 2022-12-02.
   • This test was already flaky, i.e. would occasionally fail via timeout.
   • The cause remains unknown; cannot investigate in the time available.
   • I modified ixmp.testing.jupyter.run_notebook() to accept a parameter for the timeout length in seconds (to override the default of 10), but increasing this (to e.g. 20 seconds) did not result in the test passing.
   • This PR simply skips the text on GHA / Linux.

How to review

• Read the diff and note that the CI checks all pass.

PR checklist

• [x] Continuous integration checks all ✅
• [x] Add or expand tests; coverage checks both ✅
• ~Add, expand, or update documentation.~ N/A, CI changes only
• ~Update release notes.~

[codecov[bot]]

Codecov Report

Merging #468 (a9569dd) into main (43562c1) will increase coverage by 0.0%. The diff coverage is 100.0%.

@@          Coverage Diff          @@
##            main    #468   +/-   ##
=====================================
  Coverage   98.5%   98.5%           
=====================================
  Files         42      42           
  Lines       4472    4481    +9     
=====================================
+ Hits        4408    4417    +9     
  Misses        64      64           

Impacted Files	Coverage Δ
ixmp/backend/jdbc.py	95.2% <ø> (ø)
ixmp/testing/jupyter.py	100.0% <100.0%> (ø)
ixmp/tests/test_tutorials.py	100.0% <100.0%> (ø)