Move the cached dictionary to 3.7 section

opentelemetry-api/src/opentelemetry/util/_importlib_metadata.py

@@ -17,10 +17,6 @@
 from sys import version_info
 from typing import Dict, Tuple, Union
 
-# This is a cache to avoid going through creating a dictionary for all entry
-# points for 3.7 every time the entry points function is called.
-result_entry_points_37 = {}
-
 # FIXME remove this when support for 3.7 is dropped.
 if version_info.minor == 7:
     # pylint: disable=import-error
@@ -30,6 +26,10 @@
     )
     from importlib_metadata import version
 
+    # This is a cache to avoid going through creating a dictionary for all
+    # entry points for 3.7 every time the entry points function is called.
+    result_entry_points_37 = {}
+
     def entry_points(
         group: str = None, name: str = None
     ) -> Union[Tuple[EntryPoint], Dict[str, Tuple[EntryPoint]]]: