libpq: Fix memory leak in URI parser

When an invalid query parameter is reported, some memory leaks.

found by Coverity

src/interfaces/libpq/fe-connect.c

@@ -4879,6 +4879,11 @@ conninfo_uri_parse_params(char *params,
 							  libpq_gettext(
 									"invalid URI query parameter: \"%s\"\n"),
 							  keyword);
+			if (malloced)
+			{
+				free(keyword);
+				free(value);
+			}
 			return false;
 		}
 		if (malloced)