Add VERSIONING.md, ROADMAP.md, and DEPENDENCY_POLICY.md (#2084) #578

Job	Run time
checks / test (3.11, lowest-direct, windows-latest)	3m 52s
checks / pre-commit	34s
checks / test (3.10, highest, ubuntu-latest)	47s
checks / test (3.13, highest, ubuntu-latest)	46s
checks / test (3.12, highest, windows-latest)	3m 16s
checks / test (3.13, highest, windows-latest)	2m 27s
checks / test (3.11, highest, windows-latest)	2m 40s
checks / test (3.13, lowest-direct, windows-latest)	2m 35s
checks / readme-snippets	10s
checks / test (3.11, highest, ubuntu-latest)	45s
checks / test (3.12, lowest-direct, ubuntu-latest)	49s
checks / test (3.10, lowest-direct, windows-latest)	2m 10s
checks / test (3.12, lowest-direct, windows-latest)	3m 23s
checks / test (3.10, highest, windows-latest)	2m 14s
checks / test (3.12, highest, ubuntu-latest)	52s
checks / test (3.10, lowest-direct, ubuntu-latest)	44s
checks / test (3.11, lowest-direct, ubuntu-latest)	47s
checks / test (3.13, lowest-direct, ubuntu-latest)	44s
	29m 35s

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