Tests: de-conflict ScansIScanning

Multiple runs aren't safe here...new key filter is.

StackExchange.Redis.Tests/Scans.cs

@@ -42,15 +42,16 @@ public void ScansIScanning()
         {
             using (var conn = Create(allowAdmin: true))
             {
+                var prefix = Me() + Guid.NewGuid();
                 const int DB = 7;
                 var db = conn.GetDatabase(DB);
                 var server = GetServer(conn);
                 server.FlushDatabase(DB);
                 for (int i = 0; i < 100; i++)
                 {
-                    db.StringSet("ScansRepeatable:" + i, Guid.NewGuid().ToString(), flags: CommandFlags.FireAndForget);
+                    db.StringSet(prefix + i, Guid.NewGuid().ToString(), flags: CommandFlags.FireAndForget);
                 }
-                var seq = server.Keys(DB, pageSize: 15);
+                var seq = server.Keys(DB, prefix + "*", pageSize: 15);
                 using (var iter = seq.GetEnumerator())
                 {
                     IScanningCursor s0 = (IScanningCursor)seq, s1 = (IScanningCursor)iter;