Add test to check warning not on stable version

Author: NickColley

shared/github-scripts/changelog-release-helper.unit.test.mjs

@@ -80,6 +80,24 @@ describe('Changelog release helper', () => {
       )
     })
 
+    it('does not display a warning when the change is a stable release', () => {
+      jest.mocked(fs.readFileSync).mockReturnValue(`
+        ## Unreleased
+
+        ### Fixes
+
+        Bing bong
+
+        ## v3.1.0 (Beta feature release)
+      `)
+
+      updateChangelog('3.1.1', '3.1.0')
+      expect(fs.writeFileSync).not.toHaveBeenCalledWith(
+        './CHANGELOG.md',
+        expect.stringContaining('> [!WARNING]')
+      )
+    })
+
     it('does not change the changelog if the provided version is an internal pre-release', () => {
       const consoleLogSpy = jest.spyOn(console, 'log')