polish: group FRAGMENT_VARIABLE_DEFINITION with executable defs

FRAGMENT_VARIABLE_DEFINITION was already grouped with the executable
locations, so this instead reorders that group to match upstream and the
introspection schema (INLINE_FRAGMENT before the variable definitions).

Replicates graphql/graphql-js@3cbd426

Author: Cito

src/graphql/language/directive_locations.py

@@ -15,9 +15,9 @@ class DirectiveLocation(Enum):
     FIELD = "field"
     FRAGMENT_DEFINITION = "fragment definition"
     FRAGMENT_SPREAD = "fragment spread"
+    INLINE_FRAGMENT = "inline fragment"
     VARIABLE_DEFINITION = "variable definition"
     FRAGMENT_VARIABLE_DEFINITION = "fragment variable definition"
-    INLINE_FRAGMENT = "inline fragment"
 
     # Type System Definitions
     SCHEMA = "schema"