Remove unused using directives

Author: Marco De Salvo

RDFSharp.Test/Model/RDFTripleTest.cs

@@ -16,7 +16,6 @@ limitations under the License.
 
 using RDFSharp.Model;
 using Microsoft.VisualStudio.TestTools.UnitTesting;
-using System.Threading.Tasks;
 
 namespace RDFSharp.Test.Model;
 

RDFSharp.Test/Query/Mirella/RDFQueryEngineTest.cs

@@ -32,7 +32,6 @@ limitations under the License.
 using WireMock.Util;
 using WireMock.Types;
 using System.Web;
-using System.Threading.Tasks;
 
 namespace RDFSharp.Test.Query;
 

RDFSharp.Test/Store/RDFQuadrupleTest.cs

@@ -17,7 +17,6 @@ limitations under the License.
 using RDFSharp.Model;
 using RDFSharp.Store;
 using Microsoft.VisualStudio.TestTools.UnitTesting;
-using System.Threading.Tasks;
 
 namespace RDFSharp.Test.Store;
 

RDFSharp/Model/RDFTriple.cs

@@ -16,7 +16,6 @@ limitations under the License.
 
 using System;
 using System.Collections.Generic;
-using System.Threading.Tasks;
 using RDFSharp.Query;
 
 namespace RDFSharp.Model

RDFSharp/Model/Serializers/RDFTurtle.cs

@@ -20,7 +20,6 @@ limitations under the License.
 using System.IO;
 using System.Linq;
 using System.Text;
-using System.Text.RegularExpressions;
 using RDFSharp.Query;
 
 namespace RDFSharp.Model

RDFSharp/Query/Mirella/Algebra/Expressions/RDFGeoRelateExpression.cs

@@ -16,7 +16,6 @@ limitations under the License.
 
 using System.Collections.Generic;
 using System.Text;
-using System.Text.RegularExpressions;
 using RDFSharp.Model;
 
 namespace RDFSharp.Query

RDFSharp/Store/RDFQuadruple.cs

@@ -18,7 +18,6 @@ limitations under the License.
 using RDFSharp.Query;
 using System;
 using System.Collections.Generic;
-using System.Threading.Tasks;
 
 namespace RDFSharp.Store
 {