upath: fix is_absolute on <3.12 (#256)

Author: ap--

upath/core.py

@@ -945,6 +945,9 @@ def home(cls) -> UPath:
     def absolute(self) -> Self:
         return self
 
+    def is_absolute(self) -> bool:
+        return self._flavour.isabs(str(self))
+
     def resolve(self, strict: bool = False) -> Self:
         _parts = self.parts
 

upath/tests/cases.py

@@ -115,6 +115,9 @@ def test_is_file(self):
 
         assert not (self.path / "not-existing-file.txt").is_file()
 
+    def test_is_absolute(self):
+        assert self.path.is_absolute() is True
+
     def test_is_mount(self):
         assert self.path.is_mount() is False