py_require() checks and fails on 'equal' / 'not equal' Python version requests are used

[edgararuiz]

• uv run does not accept Python version ==3.11, and ==3.09. In this change, py_require() removes any == from Python version requirements
• uv run does not accepts any combination of == requirements with non-equal requirements (>=, <=). In this change, py_require() checks and returns an informative error
• uv run does not accept more than one, different, equal-to Python version. In this change, py_require() will check and return an error this occurs
• Adds tests for the changes mentioned above, and updates tests that were sending equal and non-equal Python requirements
• Unrelated, but just found out that newer pre-release versions of packages will modify the error output (https://pypi.org/project/tensorflow/#history), so switched the tests that requests a tensorflow 2.18 against an older snapshot from expect error test.

── Failure (test-py_require.R:12:3): Error requesting newer package version against an older snapshot ──
Snapshot of code has changed:
old[9:21] vs new[9:23]
    > py_require(exclude_newer = "2024-10-20")
    > uv_get_or_create_env()
      × No solution found when resolving `--with` dependencies:
-     ╰─▶ Because only tensorflow<2.18.dev0 is available and you require
-         tensorflow>=2.18.dev0, we can conclude that your requirements are
-         unsatisfiable.
+     ╰─▶ Because only the following versions of tensorflow are available:
+             tensorflow<2.18.dev0
+             tensorflow>2.19.dev0
+         and you require tensorflow>=2.18.dev0,<2.19.dev0, we can conclude that
+         your requirements are unsatisfiable.

[t-kalinowski]

Thanks!