Pass context to tls.Dialer in tryDialWithSNI.

This cleans up resources that would otherwise be tied up by Caddy
endpoint requests where the originating TLS connection to Caddy has
went away.

V12-Ref: F-77195

src/caddy.go

@@ -81,7 +81,8 @@ func tryDialWithSNI(ctx context.Context, domain string) (bool, error) {
 	}
 
 	logc.Printf(ctx, "caddy: check TLS %s", fallbackURL)
-	connection, err := tls.Dial("tcp", connectHost, &tls.Config{ServerName: domain})
+	dialer := tls.Dialer{Config: &tls.Config{ServerName: domain}}
+	connection, err := dialer.DialContext(ctx, "tcp", connectHost)
 	if err != nil {
 		return false, err
 	}