Drop Python 3.7 support

[kushaangupta]

Closes #165

[jni]

Thanks @kushaangupta! We should also:

• add 3.10 to the list
• update the test builds in .github/workflows to not build 3.7 and build 3.10.

[kushaangupta]

Weirdly, the workflow job is interpreting 3.10 as 3.1 leading to the failures.

[jni]

Ah yes this was a common error, you need to write "3.10" in quotes so that it is interpreted as a string rather than a float.

[jni]

Thank you! 😊