Add Additional Check for NetworkX Release Candidate Versions

[nv-rliu]

Part of https://github.com/rapidsai/graph_dl/issues/579

This PR allows nx-cugraph to operate with release candidate (under development) versions of networkx

What This Pattern Allows:

• Just a single digit: 3.4, 3.9, etc

• Release Candidate format: 3.4rc0. 3.7rc2

This is needed to complete adding nightly test coverage for development branches of nx

[eriknw]

Thanks @nv-rliu, and my bad for missing this!

Btw, re.match already matches only from the beginning of the line, so beginning the pattern with "^" is not strictly necessary, but it's fine to be explicit.

[nv-rliu]

Thanks @nv-rliu, and my bad for missing this!

Btw, re.match already matches only from the beginning of the line, so beginning the pattern with "^" is not strictly necessary, but it's fine to be explicit.

Thanks for the review. And neat tip! TIL 😄

[rlratzel]

/merge