v0.23.4

Singular v0.23.4

Diff since v0.23.3

Merged pull requests:

• CI: update julia-actions/cache to v2 (#813) (@fingolfin)
• Add outdated docs warning to old versions (#814) (@lgoettgens)
• Provide a stale_age to mkpidlock (#815) (@fingolfin)
• Test against Julia 1.11-rc1 (#816) (@fingolfin)
• Bump Nemo compat (#817) (@lgoettgens)
• chore: tag 0.23.4 (#818) (@thofma)