remove support for EOL python 3.7

[w0rdsm1th]

explicitly remove support for py3.7 from setup.py and requirements.txt. build examples/environment.yml with py3.10

re issue #309

[w0rdsm1th]

n.b. I am @aleks-sch who opened #309, I just had to make changes on personal device bc I couldn't test creating the conda env from inside Schroders network

[mountainrambler]

Thanks for that. But shouldn't the version number be 2.0.0 if we follow SemVer? Also, we need to update the version number in pyproject.toml as well. But I think we can do this within a few days.

[aleks-sch]

good catch! yes v2.0.9 an oversight, will push change when I am back on personal PC (can't now due to corporate personal GH restrictions)

[mountainrambler]

Please also update the version number in pyproject.toml to 2.0.0. Thanks