e2e-tests: downgrade minimum versions

[cyphar]

libpathrs actually supports quite old versions of the languages in question (Rust 1.63, Go 1.18, and Python 3.9), but because of how the e2e-tests/cmd/* wrappers are implemented, we require higher versions in CI.

Ideally we would be testing the lowest supported version in CI, but this will require reworking quite a few of the binaries to use older versions of helper libraries (like CLI libraries in the case of Rust and Go)...