Mark the BTStackLib as unsupported (#1751)

Per https://github.com/bluekitchen/btstack/issues/529#issuecomment-1746293987
Don't run BTstackLib examples in CI

libraries/BTstackLib/src/BTstackLib.h

@@ -2,6 +2,8 @@
     Arduino Wrapper for BTstack
 */
 
+#warning The BTStackLib is no longer supported by BlueKitchen, use at your own risk
+
 #include <_needsbt.h>
 
 #ifndef __ARDUINO_BTSTACK_H

tests/common.sh

@@ -24,6 +24,7 @@ function skip_ino()
 /p13_TouchSensorLamp/
 /StringComparisonOperators/
 /PDMSerialPlotter/
+/BTstackLib/
 EOL
     echo $ino | grep -q -F "$skiplist"
     echo $(( 1 - $? ))