Add User-Agent to Modrinth request

src/main/kotlin/dev/frogmc/plugins/Routing.kt

@@ -133,7 +133,11 @@ fun Application.configureRouting() {
                         "message" to "Version not found."
                     )
                     // fetch https://api.modrinth.com/v2/version/{version} to get json
-                    val client = HttpClient()
+                    val client = HttpClient {
+                        headers {
+                            append("User-Agent", "FrogMCMeta (https://git.frogmc.dev/frogmc/meta)/1.0")
+                        }
+                    }
                     val response = client.get("https://api.modrinth.com/v2/version/${versionObj.modrinthVersion}")
                     val mrVersionString = response.body<String>()
                     val json = Json { ignoreUnknownKeys = true }