Pin pymdown-extensions back to 11.0 #3498

Job	Run time
checks / readme-snippets	13s
checks / docs	1m 7s
checks / pre-commit	48s
checks / test (3.10, lowest-direct, ubuntu-latest)	58s
checks / test (3.10, locked, windows-latest)	2m 9s
checks / test (3.11, lowest-direct, ubuntu-latest)	1m 17s
checks / test (3.12, lowest-direct, windows-latest)	2m 9s
checks / test (3.11, locked, windows-latest)	1m 46s
checks / test (3.10, lowest-direct, windows-latest)	1m 53s
checks / test (3.10, locked, ubuntu-latest)	1m 33s
checks / test (3.12, lowest-direct, ubuntu-latest)	1m 24s
checks / test (3.12, locked, windows-latest)	1m 50s
checks / test (3.11, locked, ubuntu-latest)	1m 26s
checks / test (3.12, locked, ubuntu-latest)	1m 19s
checks / test (3.14, locked, ubuntu-latest)	1m 20s
checks / test (3.13, locked, ubuntu-latest)	1m 20s
checks / test (3.13, lowest-direct, windows-latest)	1m 35s
checks / test (3.14, locked, windows-latest)	2m 19s
checks / test (3.13, lowest-direct, ubuntu-latest)	1m 21s
checks / test (3.11, lowest-direct, windows-latest)	1m 48s
checks / test (3.14, lowest-direct, windows-latest)	1m 52s
checks / test (3.13, locked, windows-latest)	1m 50s
checks / test (3.14, lowest-direct, ubuntu-latest)	1m 22s
all-green	3s
	34m 42s

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