GDScript: Allow usage of literal false in assert without a warning

modules/gdscript/tests/scripts/analyzer/features/assert_literal_false.gd

@@ -0,0 +1,6 @@
+func test():
+	var never: Variant = false
+	if never:
+		assert(false)
+		assert(false, 'message')
+	print('ok')

modules/gdscript/tests/scripts/analyzer/features/assert_literal_false.out

@@ -0,0 +1,2 @@
+GDTEST_OK
+ok