DEP: Drop Python 3.7 Support

[snowman2]

Community references:

• NEP-29 says numpy dropped support for Python 3.7 in December 2021.
• pandas (Drop support for Python 3.7 pandas-dev/pandas#41678)
• opendatacube is Python 3.8+ already ref
• django ref
• pyproj (DEP: Python 3.7 support pyproj4/pyproj#930)
• rioxarray (DEP: Drop Python 3.7 support corteva/rioxarray#451)

[keewis]

this will be done in #5892. We can discuss this in the call tomorrow, so unless there's any objections we should be able to merge afterwards.