Update networkx requirement from <=2.5 to <3.1 (#108)

Updates the requirements on [networkx](https://github.com/networkx/networkx) to permit the latest version.
- [Release notes](https://github.com/networkx/networkx/releases)
- [Commits](networkx/networkx@networkx-0.23...networkx-3.0)

---
updated-dependencies:
- dependency-name: networkx
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: Jan Ernsting <j.ernsting@uni-muenster.de>

requirements.txt

@@ -1,5 +1,5 @@
 photonai
-networkx<=2.5
+networkx<3.1
 pydot
 dgl==1.0.0
 nxt-gem