Update Npgsql to 7.0.7 for net6 (#2214)

## Why make this change?

- Closes #2206
- As noted in #2207, now that false positive vulnerability alert no
longer shows due to correct patched versions being recognized by dotnet
restore.
- Merging Directory to 1.1 branch.

## What is this change?

- For .net6 updates npgsql to 7.0.7.
- Removes "ignore" tag on serialization/deserialization test that broke
because of the npgsql version used.

## How was this tested?
- [x] Unit Tests 
- `dotnet format` step passes without dotnet restore vulnerability
alert.
- unit test `TestDictionaryDatabaseObjectSerializationDeserialization`
unignored

Author: seantleonard

src/Directory.Packages.props

@@ -64,7 +64,6 @@
     <PackageVersion Include="Microsoft.AspNetCore.TestHost" Version="6.0.29" />
     <PackageVersion Include="Microsoft.Extensions.Configuration.Json" Version="6.0.0" />
     <PackageVersion Include="Microsoft.Extensions.Configuration.Binder" Version="6.0.0" />
-    <!--Once dotnet restore properly resolves that 'Npgsql' 7.0.7 is not vulnerable, set this ref to 7.0.7.-->
-    <PackageVersion Include="Npgsql" Version="8.0.3" />
+    <PackageVersion Include="Npgsql" Version="7.0.7" />
   </ItemGroup>
 </Project>

src/Service.Tests/Unittests/SerializationDeserializationTests.cs

@@ -259,9 +259,6 @@ public void TestColumnDefinitionNegativeCases()
         /// Temporarily ignore test for .net6 due to npgsql issue.
         /// </summary>
         [TestMethod]
-#if NET6_0
-        [Ignore]
-#endif
         public void TestDictionaryDatabaseObjectSerializationDeserialization()
         {
             InitializeObjects();