993 progress: convert two more files to pytest, only three remaining (stac-utils#1534)

* 993 whoops forgot to take out dev notes

* 993 start on test_sat.py conversion to pytest

* 993 convert test_sat.py's assertions to pytest

* 993 move sat_test.py cassettes to new pytest names

* 993 set up fixtures & demo with a few tests

* 993 nonfunctional declassing

* 993 rewrite to use `item` fixture instead of `self.item` from setUp

* 993 rewrite tests to use new sentinel_item fixture

* 993 SatTest stragglers; conversion finished

* 993 start conversion of SatSummariesTest

* 993 declass last of test_sat.py

* 993 finish converting SatSummariesTest

* 993 pre-commit faff

* 993 start on test_scientific.py: convert assertions & a few tests

* 993 rename cassettes for pytest conversion

* 993 make a fixture & test it

* 993 finish converting ItemScientificExtensionTest

* 993 refactor

* 993 start converting CollectionScientificExtensionTest

* 993 declass CollectionScientificExtensionTest (nonfunctional)

* 993 dedupe test names

* 993 convert two outlier tests

* 993 start using new fixture

* 993 rename cassettes

* 993 missed a few straggler assertions

* 993 refactor to prep for last declassing

* 993 declass once more

* 993 ruff really made the code better by alphabetizing the imports

Author: teks