bump ninja to 1.13.1

[dimpase]

a long overdue update - in particular, to version compatible with the make's jobobserver
Appears to reduce/eliminate doctest breakage due to warnings about jobobserver.
Thanks @orlitzky for pointing it out

📝 Checklist

• The title is concise and informative.
• The description explains in detail what this PR is about.
• I have linked a relevant issue or discussion.
• I have created tests covering the changes.
• I have updated the documentation and checked the documentation preview.

⌛ Dependencies

[dimpase]

@jhpalmieri This should eliminate a class of test errors you observe.

[github-actions]

Documentation preview for this PR (built with commit cd81fc7; changes) is ready! 🎉
This preview will update shortly after each push to this PR.

[dimpase]

testing of 10.8.beta5 with this fix on macOS with Homebrew shows relatively few test errors:

src/bin/sage -t --warn-long 5.0 --random-seed=286351001085036431132636814763243651762 src/sage/libs/singular/function.pyx  # 2 doctests failed
src/bin/sage -t --warn-long 5.0 --random-seed=286351001085036431132636814763243651762 src/sage/rings/real_mpfr.pyx  # 1 doctest failed
src/bin/sage -t --warn-long 5.0 --random-seed=286351001085036431132636814763243651762 src/sage/rings/polynomial/polynomial_singular_interface.py  # 1 doctest failed
src/bin/sage -t --warn-long 5.0 --random-seed=286351001085036431132636814763243651762 src/sage/rings/polynomial/msolve.py  # 14 doctests failed
src/bin/sage -t --warn-long 5.0 --random-seed=286351001085036431132636814763243651762 src/sage/rings/polynomial/multi_polynomial_ideal.py  # 2 doctests failed
src/bin/sage -t --warn-long 5.0 --random-seed=286351001085036431132636814763243651762 src/sage/interfaces/singular.py  # 1 doctest failed
src/bin/sage -t --warn-long 5.0 --random-seed=286351001085036431132636814763243651762 src/sage/interfaces/fricas.py  # 1 doctest failed

[jhpalmieri]

Upgrading the version of ninja_build is fine with me, but unfortunately this does not fix the problems I'm seeing. It turns out that I've been building with homebrew's version of ninja, which is already 1.13.1; using the branch here with ./configure --with-system-ninja_build=no built the version here and presumably used it, and I get the same error messages as before.