Bump NUnit from 4.4.0 to 4.5.0 (#86)

Author: dependabot[bot]

MimeTypes.Tests/MimeTypes.Tests.csproj

@@ -11,7 +11,7 @@
     </PropertyGroup>
 
     <ItemGroup>
-        <PackageReference Include="NUnit" Version="4.4.0" />
+        <PackageReference Include="NUnit" Version="4.5.0" />
         <PackageReference Include="NUnit3TestAdapter" Version="6.1.0" />
         <PackageReference Include="Microsoft.NET.Test.Sdk" Version="18.0.1" />
     </ItemGroup>