Add @stable virtual dist-tag when installing test-framework package

After July 2024, specifying the `@latest` dist-tag (default) will install the test-framework package v2.

`@stable` virtual dist-tag is support from opeupm-cli v4.3.0 or later.
see: openupm/openupm-cli#395

Makefile

@@ -97,7 +97,7 @@ create_project:
 	  -batchmode \
 	  -quit
 	touch UnityProject~/Assets/.gitkeep
-	openupm -c $(PROJECT_HOME) add -f com.unity.test-framework
+	openupm -c $(PROJECT_HOME) add -f com.unity.test-framework@stable
 	openupm -c $(PROJECT_HOME) add -f com.unity.testtools.codecoverage
 	openupm -c $(PROJECT_HOME) add -f com.cysharp.unitask
 	openupm -c $(PROJECT_HOME) add -f com.nowsprinting.test-helper.monkey