fix: use correct http method format in functions_client

close #1149

Author: Vinzent03

packages/functions_client/lib/src/functions_client.dart

@@ -113,11 +113,11 @@ class FunctionsClient {
       );
       final fields = body as Map<String, String>?;
 
-      request = http.MultipartRequest(method.name, uri)
+      request = http.MultipartRequest(method.value, uri)
         ..fields.addAll(fields ?? {})
         ..files.addAll(files);
     } else {
-      final bodyRequest = http.Request(method.name, uri);
+      final bodyRequest = http.Request(method.value, uri);
 
       final String? bodyStr;
       if (body == null) {

packages/functions_client/lib/src/types.dart

@@ -4,11 +4,15 @@ import 'dart:typed_data';
 import 'package:http/http.dart';
 
 enum HttpMethod {
-  get,
-  post,
-  put,
-  delete,
-  patch,
+  get("GET"),
+  post("POST"),
+  put("PUT"),
+  delete("DELETE"),
+  patch("PAtch");
+
+  /// The uppercase HTTP method name. This should be used for a [Request]
+  final String value;
+  const HttpMethod(this.value);
 }
 
 class FunctionResponse {