fix: change overpass turbo API used to retrieve data

src/AddressData.Core/Constants.cs

@@ -3,7 +3,10 @@
 public static class Constants
 {
     // Overpass Turbo Queries
-    public const string OverpassTurboUrl = "https://maps.mail.ru/osm/tools/overpass/api/interpreter";
+    /// <summary>
+    /// Retrieved from https://wiki.openstreetmap.org/wiki/Overpass_API#Public_Overpass_API_instances
+    /// </summary>
+    public const string OverpassTurboUrl = "https://overpass-api.de/api/interpreter";
     public const string OverpassTurboGetAllCitiesQuery =
         "?data=[out:csv(::id,\"name\",\"name:en\";true;\",\")];area[place=\"city\"];out;";
     public static string OverpassTurboGetCityQuery(long areaId) =>

tests/AddressData.UnitTests/Services/DocumentServiceTests.cs

@@ -380,7 +380,7 @@ public async Task InsertAsyncAllowsCustomIEnumerableTypes()
         var doc = await _documentService.InsertAsync(arrayWriteModel, location);
 
         Assert.That(doc, Is.Not.Null);
-        Assert.That(doc!.Size, Is.EqualTo(2));
+        Assert.That(doc.Size, Is.EqualTo(2));
 
         var fileName = Path.Combine("output", location.Country, location.State, $"{location.City}.csv");
         var lines = await File.ReadAllLinesAsync(fileName);

tests/AddressData.UnitTests/Services/SeedingServiceTests.cs

@@ -254,7 +254,7 @@ public async Task AddCityReturnsDocumentFromDocumentServiceWhenAllValid()
 
         // Assert
         Assert.That(result, Is.Not.Null);
-        Assert.That(result!.Size, Is.EqualTo(999));
+        Assert.That(result.Size, Is.EqualTo(999));
 
         _overpassTurboServiceMock.VerifyAll();
         _documentServiceMock.VerifyAll();
@@ -469,7 +469,7 @@ public async Task AddCityCalledTwiceForSameAreaIdProducesSameResultIfDocumentSer
 
         using (Assert.EnterMultipleScope())
         {
-            Assert.That(first!.Size, Is.EqualTo(second!.Size));
+            Assert.That(first.Size, Is.EqualTo(second.Size));
             Assert.That(first.City, Is.EqualTo(second.City));
         }