Use "read" as default scope for Strava (#443)

Based on https://developers.strava.com/docs/authentication/ there is no "public" scope for Strava.

Author: bryantlikes

src/AspNet.Security.OAuth.Strava/StravaAuthenticationOptions.cs

@@ -25,7 +25,7 @@ public StravaAuthenticationOptions()
             TokenEndpoint = StravaAuthenticationDefaults.TokenEndpoint;
             UserInformationEndpoint = StravaAuthenticationDefaults.UserInformationEndpoint;
 
-            Scope.Add("public");
+            Scope.Add("read");
 
             ClaimActions.MapJsonKey(ClaimTypes.NameIdentifier, "id");
             ClaimActions.MapJsonKey(ClaimTypes.Name, "username");