Use Union rather than pipe for type annotation for Python 3.9.

glue_ar/registries.py

@@ -1,5 +1,5 @@
 from collections.abc import Callable
-from typing import Tuple, Type
+from typing import Tuple, Type, Union
 
 from glue.config import DictRegistry
 
@@ -9,14 +9,14 @@
 
 class BuilderRegistry(DictRegistry):
 
-    def add(self, extensions: str | Tuple[str], builder: Type):
+    def add(self, extensions: Union[str, Tuple[str]], builder: Type):
         if isinstance(extensions, str):
             self._members[extensions] = builder
         else:
             for ext in extensions:
                 self._members[ext] = builder
 
-    def __call__(self, extensions: str | Tuple[str]):
+    def __call__(self, extensions: Union[str, Tuple[str]]):
         def adder(builder: Type):
             self.add(extensions, builder)
         return adder