Set the current culture to invariant culture for consistent numeric f…

…ormatting across different environments. This is crucial because the output of string formatting for numbers can vary based on the machine's locale settings. Using the invariant culture ensures that the format "12,345.00" will be consistent regardless of the regional settings of the system on which this test runs. (#49)

OpenXMLTemplatesTest/Variables/VariableSourceTests.cs

@@ -1,4 +1,5 @@
 using System.Collections.Generic;
+using System.Globalization;
 using NUnit.Framework;
 using OpenXMLTemplates.Variables;
 using OpenXMLTemplates.Variables.Exceptions;
@@ -47,6 +48,9 @@ public void Format_Numeric_Fields_Value_Null()
         [Test]
         public void Format_Numeric_Fields()
         {
+            // Set the current culture to invariant culture for consistent numeric formatting across different environments. 
+            CultureInfo.CurrentCulture = CultureInfo.InvariantCulture;
+
             var data = new Dictionary<string, object>
             {
                 { "prices", new List<string> { "123", "12345.0001" } }