[TECH DEBT] Update relenv to 0.20.5

[dwoz]

There has been a new release of relenv which upgrades some dependencies.

Update gdbm from 1.25 to 1.26
Update libffi from 3.5.1 to 3.5.2
Update readline from 8.2.13 to 8.3
Update sqlite from 3.50.2 to 3.50.4
Update sqlite on windows from 3.40.1 to 0.35.4 (CVE-2025-6965)