(GH-108) Fixed missing github actions check

The github actions ci detector was not added to the pipeline
of which CIs we iterate through. This commit fixes this
by adding it to the array.

fixes #108

Source/Codecov/Factories/ContinuousIntegrationServerFactory.cs

@@ -1,4 +1,4 @@
-using System.Linq;
+using System.Linq;
 using Codecov.Services.ContinuousIntegrationServers;
 
 namespace Codecov.Factories
@@ -7,7 +7,7 @@ internal static class ContinuousIntegrationServerFactory
     {
         public static IContinuousIntegrationServer Create()
         {
-            var continuousIntegrationServers = new IContinuousIntegrationServer[] { new AppVeyor(), new Travis(), new TeamCity(), new AzurePipelines(), new Jenkins() };
+            var continuousIntegrationServers = new IContinuousIntegrationServer[] { new AppVeyor(), new Travis(), new TeamCity(), new AzurePipelines(), new Jenkins(), new GitHubAction() };
             var buildServer = continuousIntegrationServers.FirstOrDefault(x => x.Detecter);
             return buildServer ?? new ContinuousIntegrationServer();
         }

Source/Codecov/Services/ContinuousIntegrationServers/ContinuousIntegrationServer.cs

@@ -65,7 +65,7 @@ protected bool CheckEnvironmentVariables(params string[] environmentVariables)
 
         public virtual string GetEnvironmentVariable(string name)
         {
-            if (UserEnvironmentVariables?.ContainsKey(name) == true)
+            if (UserEnvironmentVariables != null && UserEnvironmentVariables.ContainsKey(name))
             {
                 return UserEnvironmentVariables[name];
             }