Add test case for beta version in release notes validation

Author: tsuzu

hack/tools/release/notes/main_test.go

@@ -261,6 +261,16 @@ func Test_validateConfig(t *testing.T) {
 			},
 			wantErr: false,
 		},
+		{
+			name: "Valid previousReleaseVersion with beta in ref format",
+			args: &notesCmdConfig{
+				fromRef:                "ref1/tags",
+				toRef:                  "ref2/tags",
+				newTag:                 "v1.0.0",
+				previousReleaseVersion: "tags/v1.0.0-beta.1",
+			},
+			wantErr: false,
+		},
 		{
 			name: "Invalid previousReleaseVersion without pre-release in ref format",
 			args: &notesCmdConfig{