Drop Python version range enforcement from PythonVersion::from_str (#7264)

This caused some problems earlier, as it prevented us from _listing_
Python versions <3.7 which seems weird (see
#7131 (comment))

I'm worried that without this the changes to installation key parsing in
#7263 would otherwise be too
restrictive.

I think if we want to enforce these ranges, we should do so separately
from the parse step.

Author: zanieb

crates/uv-python/src/python_version.rs

@@ -31,12 +31,6 @@ impl FromStr for PythonVersion {
         if version.epoch() != 0 {
             return Err(format!("Python version `{s}` has a non-zero epoch"));
         }
-        if version.version < Version::new([3, 7]) {
-            return Err(format!("Python version `{s}` must be >= 3.7"));
-        }
-        if version.version >= Version::new([4, 0]) {
-            return Err(format!("Python version `{s}` must be < 4.0"));
-        }
 
         Ok(Self(version))
     }