Apply ruff formatting to test files

[mielvds]

This PR makes the test files comply with the ruff linter and formatter.

• formatting was applied to all test files
• some parts of the code were updated to more modern python, like format strings, exception suppress, exception chaining
• the Python 2 BW-compatible code for reading files was removed from tests/runtests.py. This is not breaking because everything below 3.10 is no longer supported anyway.
• renamed the equalUnordered to the more pythonic equal_unordered. Linter errors on camelCase naming in unittest class extensions are ignored because that would break the extension.

[github-actions]

Coverage Report

File	Stmts	Miss	Cover	Missing
lib/pyld
canon.py	219	4	98%	26, 176, 553–554
context_resolver.py	102	8	92%	70, 129, 143, 189, 195–197, 221
iri_resolver.py	141	3	98%	307–308, 318
jsonld.py	2432	170	93%	254–258, 339, 376, 381, 391, 408–420, 456–457, 499, 505, 523, 531–532, 643–647, 726–727, 742–743, 805–809, 833–834, 847–848, 858–859, 884–885, 924, 932, 938–942, 952–953, 987, 996, 1001, 1064, 1085, 1105–1107, 1117–1121, 1136, 1154, 1159–1160, 1257–1260, 1281, 1333, 1337, 1375, 1416, 1433–1436, 1444, 1480, 1576–1580, 1603–1605, 1610, 1622–1625, 1759, 1774, 2125, 2132–2137, 2196, 2217, 2235, 2242, 2676, 2722, 2725, 2775, 2846, 2874, 2880, 3110, 3116, 3118, 3154, 3305–3309, 3376, 3412, 3456, 3634–3635, 3647, 3889, 4016, 4038, 4067–4070, 4094–4095, 4269, 4332, 4354, 4424, 4426, 4442, 4530, 4572, 4768, 4770, 4805, 4807, 4816, 4930, 5039, 5118, 5235–5243, 5301–5307, 5373, 5582, 5587–5591, 5631, 5634, 5713–5714, 5722
lib/pyld/documentloader
aiohttp.py	65	22	66%	28–38, 69, 75, 87, 99–107, 118–121, 138, 153–155
requests.py	41	5	88%	55, 69, 81–89
TOTAL	3154	212	93%

Tests	Skipped	Failures	Errors	Time
1652	59 💤	0 ❌	0 🔥	11.387s ⏱️