Make the per-version wire packages private (`mcp_types._v*`) #3698

Job	Run time
checks / docs	58s
checks / readme-snippets	16s
checks / pre-commit	47s
checks / test (3.12, locked, windows-latest)	1m 50s
checks / test (3.11, lowest-direct, ubuntu-latest)	1m 25s
checks / test (3.13, locked, windows-latest)	2m 0s
checks / test (3.13, locked, ubuntu-latest)	1m 13s
checks / test (3.14, locked, windows-latest)	1m 56s
checks / test (3.10, locked, ubuntu-latest)	1m 28s
checks / test (3.12, lowest-direct, ubuntu-latest)	1m 30s
checks / test (3.10, lowest-direct, ubuntu-latest)	1m 11s
checks / test (3.10, locked, windows-latest)	2m 14s
checks / test (3.14, lowest-direct, windows-latest)	2m 1s
checks / test (3.12, lowest-direct, windows-latest)	1m 54s
checks / test (3.13, lowest-direct, windows-latest)	2m 3s
checks / test (3.12, locked, ubuntu-latest)	1m 38s
checks / test (3.10, lowest-direct, windows-latest)	1m 36s
checks / test (3.11, locked, ubuntu-latest)	1m 26s
checks / test (3.11, locked, windows-latest)	1m 57s
checks / test (3.14, locked, ubuntu-latest)	1m 18s
checks / test (3.14, lowest-direct, ubuntu-latest)	1m 23s
checks / test (3.13, lowest-direct, ubuntu-latest)	1m 18s
checks / test (3.11, lowest-direct, windows-latest)	1m 58s
all-green	4s
	35m 24s

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