Added readonly to fields that are never modified (#2759)

Co-authored-by: Lehonti Ramos <john@doe>
Co-authored-by: Keegan Campbell <me@kfcampbell.com>

Octokit.Tests.Integration/Helpers/EnterpriseUserContext.cs

@@ -17,7 +17,7 @@ namespace Octokit.Tests.Integration.Helpers
             UserEmail = user.Email;
         }
 
-        private IConnection _connection;
+        private readonly IConnection _connection;
         internal int UserId { get; private set; }
         internal string UserLogin { get; private set; }
         internal string UserEmail { get; private set; }

Octokit.Tests.Integration/Helpers/GpgKeyContext.cs

@@ -17,7 +17,7 @@ namespace Octokit.Tests.Integration.Helpers
             PublicKeyData = key.PublicKey;
         }
 
-        private IConnection _connection;
+        private readonly IConnection _connection;
         internal int GpgKeyId { get; set; }
         internal string KeyId { get; set; }
         internal string PublicKeyData { get; set; }

Octokit.Tests.Integration/Helpers/MaintenanceModeContext.cs

@@ -17,7 +17,7 @@ namespace Octokit.Tests.Integration.Helpers
             EnterpriseHelper.SetMaintenanceMode(_connection, enabled);
         }
 
-        private IConnection _connection;
+        private readonly IConnection _connection;
 
         public void Dispose()
         {

Octokit.Tests.Integration/Helpers/PublicKeyContext.cs

@@ -17,7 +17,7 @@ namespace Octokit.Tests.Integration.Helpers
             KeyData = key.Key;
         }
 
-        private IConnection _connection;
+        private readonly IConnection _connection;
         internal int KeyId { get; private set; }
         internal string KeyTitle { get; private set; }
         internal string KeyData { get; private set; }

Octokit.Tests.Integration/Helpers/RepositoryContext.cs

@@ -19,7 +19,7 @@ namespace Octokit.Tests.Integration.Helpers
             RepositoryDefaultBranch = repo.DefaultBranch;
         }
 
-        private IConnection _connection;
+        private readonly IConnection _connection;
         internal long RepositoryId { get; private set; }
         internal string RepositoryOwner { get; private set; }
         internal string RepositoryName { get; private set; }

Octokit.Tests.Integration/Helpers/TeamContext.cs

@@ -15,7 +15,7 @@ namespace Octokit.Tests.Integration.Helpers
             Invitations = new List<string>();
         }
 
-        private IConnection _connection;
+        private readonly IConnection _connection;
         internal int TeamId { get; private set; }
         internal string TeamName { get; private set; }