fix: Incorrect endpoint in UploadStrings method (#344)

Author: Seppe-Ottevaere

src/Crowdin.Api/SourceStrings/SourceStringsApiExecutor.cs

@@ -1,4 +1,4 @@
-
+
 using System.Collections.Generic;
 using System.Net;
 using System.Threading.Tasks;
@@ -180,7 +180,7 @@ private static string FormUrl_StringId(long projectId, long stringId)
 
         private static string FormUrl_StringsUpload(long projectId)
         {
-            return $"/projects/{projectId}/strings/upload";
+            return $"/projects/{projectId}/strings/uploads";
         }
 
         private static string FormUrl_StringsUploadId(long projectId, string uploadId)

tests/Crowdin.Api.UnitTesting/Tests/SourceStrings/SourceStringsApiTests.cs

@@ -1,4 +1,4 @@
-
+
 using System;
 using System.Collections.Generic;
 using System.Linq;
@@ -154,7 +154,7 @@ public async Task UploadStrings()
 
             Mock<ICrowdinApiClient> mockClient = TestUtils.CreateMockClientWithDefaultParser();
 
-            var url = $"/projects/{projectId}/strings/upload";
+            var url = $"/projects/{projectId}/strings/uploads";
 
             mockClient
                 .Setup(client => client.SendPostRequest(url, request, null))