add clean

Author: soutaro

.github/workflows/ruby.yml

@@ -21,7 +21,7 @@ jobs:
           - ruby: head
             job: stdlib_test rubocop
           - ruby: head
-            job: compile_c99
+            job: clean compile_c99
           - ruby: "3.4"
             job: stdlib_test
           - ruby: "3.4"
@@ -37,7 +37,7 @@ jobs:
           - ruby: "3.4"
             job: typecheck_test
           - ruby: "3.4"
-            job: compile_c99
+            job: clean compile_c99
     env:
       RANDOMIZE_STDLIB_TEST_ORDER: "true"
     steps: