pythongh-131196: Improve perfomance of UUID.hex and UUID.__str__ by ~10% (python#131197)

Results before and after the fix:

```
hex
before: 0.021755493999989994
after:  0.01465080400066654 

str
before: 0.06381790500017814
after:  0.05134949700004654
```

Co-authored-by: Bénédikt Tran <[email protected]>

Author: 2 people

Lib/uuid.py

@@ -321,9 +321,8 @@ def __setattr__(self, name, value):
         raise TypeError('UUID objects are immutable')
 
     def __str__(self):
-        hex = '%032x' % self.int
-        return '%s-%s-%s-%s-%s' % (
-            hex[:8], hex[8:12], hex[12:16], hex[16:20], hex[20:])
+        x = self.hex
+        return f'{x[:8]}-{x[8:12]}-{x[12:16]}-{x[16:20]}-{x[20:]}'
 
     @property
     def bytes(self):
@@ -387,7 +386,7 @@ def node(self):
 
     @property
     def hex(self):
-        return '%032x' % self.int
+        return self.bytes.hex()
 
     @property
     def urn(self):

Misc/NEWS.d/next/Library/2025-03-13-19-53-57.gh-issue-131196.3sBFv2.rst

@@ -0,0 +1 @@
+Improve perfomance of :attr:`uuid.UUID.hex` and :meth:`uuid.UUID.__str__ <object.__str__>`.