chore: bump toolchain to v4.1.0 (leanprover-community#7369)

Co-authored-by: Scott Morrison <[email protected]>

chore: bump to Lean v4.0.0 (leanprover-community#7024)

Co-authored-by: Scott Morrison <[email protected]>

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This commit is the last that is guaranteed to be synchronized with ma…

…thlib3