Issue #11850 - Add sys.last_exc

[robotherapist]

Closes #11850

[robotherapist]

@bluetech Does this require updating mypy? The error in pre-commit.ci is:

ruff.....................................................................Passed
ruff-format..............................................................Passed
trim trailing whitespace.................................................Passed
fix end of files.........................................................Passed
fix python encoding pragma...............................................Passed
check yaml...............................................................Passed
debug statements (python)................................................Passed
blacken-docs.............................................................Passed
setup-cfg-fmt............................................................Passed
type annotations not comments............................................Passed
mypy.....................................................................Failed
- hook id: mypy
- exit code: 1

src/_pytest/runner.py:172: error: Module has no attribute "last_exc"  [attr-defined]
src/_pytest/runner.py:182: error: Module has no attribute "last_exc"  [attr-defined]
testing/test_runner.py:930: error: Module has no attribute "last_exc"  [attr-defined]
Found 3 errors in 2 files (checked 232 source files)

rst......................................................................Passed
changelog filenames..................................(no files to check)Skipped
py library is deprecated.................................................Passed
py.path usage is deprecated..............................................Passed

Weird it ran the first time though... I was hoping the if statements for 3.12.0 would satisfy everything.

[bluetech]

Merged through #12027, thanks @robotherapist.