Tweak upgrade script, just to be safe.

Author: esabol

Diff for: upgrade_scripts/pg_sphere--1.3.1--1.3.2.sql.in

@@ -28,7 +28,7 @@ COMMENT ON FUNCTION spoly(float8[]) IS
    'creates spoly from array of numbers in radians';
 
 -- add PARALLEL SAFE to spoly_deg(float8[])
-ALTER FUNCTION spoly_deg(float8[]) PARALLEL SAFE;
+ALTER FUNCTION spoly_deg(float8[]) IMMUTABLE STRICT PARALLEL SAFE;
 
 -- update comment on spoly_deg function
 COMMENT ON FUNCTION spoly_deg(float8[]) IS