993 progress: convert 3 more files; 10 to go (stac-utils#1531)

* 993 hand-convert a few tests & prep for mass conversion

* 993 convert assertions to pytest style

* 993 clean up rough formatting by ruff

* 993 Force mypy to be quiet

* 993 convert some non-vcr tests

* 993 move cassettes to their new names

* 993 convert rest of ProjectionTest

* 993 start converting test_grid.py by renaming cassettes

* 993 non-functional declassing of test_grid.py

* 993 convert test_grid.py's assertions

* 993 complete test_grid.py conversion

* 993 whoops forgot a class in test_projection.py; declass it

* 993 finish conversion of projection summaries

* 993 pre-commit faff

* 993 nonfunctional declassing in test_table.py

* 993 finish conversion of test_table.py

* 993 pre-commit fixups

* 993 refactor & cleanup

Author: teks