Fix pre-release exclusive comparison operator in uv-pep440 (#12836)
From PEP 440:
> The exclusive ordered comparison <V MUST NOT allow a pre-release of
the specified version unless the specified version is itself a
pre-release. Allowing pre-releases that are earlier than, but not equal
to a specific pre-release may be accomplished by using <V.rc1 or
similar.
We had an additional check that would block this even if the specifier
did have a pre-release.
This likely didn't show up earlier because `Ranges` uses different code
in the resolver.
I checked these changes against `packaging` to verify their behavior:
```python
print(SpecifierSet("<1").contains("1a1", prereleases=True)) # False
print(SpecifierSet("<1a2").contains("1a1", prereleases=True)) # True
print(SpecifierSet("<1").contains("1dev1", prereleases=True)) # False
print(SpecifierSet("<1dev2").contains("1dev1", prereleases=True)) # True
print(SpecifierSet("<1a2").contains("1dev1", prereleases=True)) # True
```
Closes #12834
