Generalise n2p2 version check

[ElliottKasoar]

We currently check two hard-coded versions of n2p2: https://github.com/stfc/CC_HDNNP/blob/main/src/cc_hdnnp/active_learning.py#L1012. As this is based on a bug fix introduced in v2.1.1, we may instead be able to check that the current version is more recent than this, preventing the need to continue to add further versions manually.

[ElliottKasoar]

Relatively minor, but also note that the current return description has not been updated with the newest version check: https://github.com/stfc/CC_HDNNP/blob/main/src/cc_hdnnp/active_learning.py#L996, and similarly for the parameter description when extrapolation_format is passed to _read_log: https://github.com/stfc/CC_HDNNP/blob/main/src/cc_hdnnp/active_learning.py#L1051.

These would require further changes for a more general check.