move magic string to constants

Author: jimmylewis

src/LibraryManager/Cache/WebRequestHandler.cs

@@ -62,7 +62,7 @@ private HttpClient CreateHttpClient(string url)
 #pragma warning disable CA2000 // Dispose objects before losing scope
             var httpMessageHandler = new HttpClientHandler();
 #pragma warning restore CA2000 // Dispose objects before losing scope
-            if (_settings.TryGetValue("forcetls12", out string value) && value.Length > 0)
+            if (_settings.TryGetValue(Constants.ForceTls12, out string value) && value.Length > 0)
             {
                 httpMessageHandler.SslProtocols = System.Security.Authentication.SslProtocols.Tls12;
             }

src/LibraryManager/Configuration/Constants.cs

@@ -17,5 +17,6 @@ internal class Constants
         public const string HttpsProxyPassword = "https_proxy.password";
         public const string HttpsProxyBypass = "https_proxy.bypass";
 
+        public const string ForceTls12 = "forcetls12";
     }
 }