docs: update python version in contributor guide (#248)

Fixes: #246

.github/CONTRIBUTING.md

@@ -1,7 +1,6 @@
 # Contributing to oaipmh-scythe
 
-Contributions are welcome, and they are greatly appreciated! Every little bit
-helps, and credit will always be given.
+Contributions are welcome, and they are greatly appreciated! Every little bit helps, and credit will always be given.
 
 You can contribute in many ways.
 
@@ -45,7 +44,7 @@ If you are proposing a feature:
 
 Ready to contribute?
 
-You need Python 3.8+ and [hatch](https://github.com/pypa/hatch). You can install it globally with [pipx](https://github.com/pypa/pipx):
+You need Python 3.10+ and [hatch](https://github.com/pypa/hatch). You can install it globally with [pipx](https://github.com/pypa/pipx):
 
 ```console
 $ pipx install hatch
@@ -99,7 +98,7 @@ Before you submit a pull request, check that it meets these guidelines:
 1. The pull request should include tests.
 2. If the pull request adds functionality, the docs should be updated. Put
    your new functionality into a function with a docstring.
-3. The pull request should work for Python >= 3.8. Check
+3. The pull request should work for Python >= 3.10. Check
    https://github.com/afuetterer/oaipmh-scythe/pulls
    and make sure that all the tests pass.