chg: test: Add utility module to import correct version of hypothesis

On FIPS-enabled platforms, we need to ensure a minimal version of
hypothesis which no longer uses MD5. This doesn't need to be enforced
for other platforms.

Move the import magic to a utility module to avoid copy-pasting the
boilerplate code around.

Merge branch 'nicki/pytest-import-hypothesis' into 'main'

See merge request isc-projects/bind9!10442