Add duplicate name check to registry data file validator

The registry data file must be manually edited when a library name change request is received. Each library must have a
unique name, so it's important to verify that no duplicates are introduced through these edits.

.github/workflows/assets/validate-registry/main.go

@@ -39,7 +39,16 @@ func main() {
 	}
 
 	if !reflect.DeepEqual(rawRepos, filteredRepos) {
-		fmt.Fprintln(os.Stderr, "error: Registry data file contains duplicate entries")
+		fmt.Fprintln(os.Stderr, "error: Registry data file contains duplicate URLs")
 		os.Exit(1)
 	}
+
+	nameMap := make(map[string]bool)
+	for _, entry := range rawRepos {
+		if _, found := nameMap[entry.LibraryName]; found {
+			fmt.Fprintf(os.Stderr, "error: Registry data file contains duplicates of name %s\n", entry.LibraryName)
+			os.Exit(1)
+		}
+		nameMap[entry.LibraryName] = true
+	}
 }

.github/workflows/assets/validate-registry/tests/test_all.py

@@ -31,6 +31,7 @@ test_data_path = pathlib.Path(__file__).resolve().parent.joinpath("testdata")
         ("invalid-data-format.txt", False),
         ("invalid-url-format.txt", False),
         ("duplicate-url.txt", False),
+        ("duplicate-name.txt", False),
         ("valid.txt", True),
     ],
 )

.github/workflows/assets/validate-registry/tests/testdata/duplicate-name.txt

@@ -0,0 +1,4 @@
+https://github.com/arduino-libraries/Scheduler.git|Arduino|Scheduler
+https://github.com/arduino-libraries/SD.git|Partner|SD
+https://github.com/arduino-libraries/Servo.git|Recommended|Servo
+https://github.com/arduino-libraries/Foo.git|Contributed|SD