some minor cleanups

* Suppress warnings about conflicting library names in platformio.ini by
  explicitly picking the libraries by id that we want.
* fix unused static function warning by making it not static ;)
* declare arduino-fsm as dependency for BluetoothOTA. Hopefully this
  fixes the CI builds?

Tested: `pio run` builds.

src/PowerFSM.h

@@ -1,6 +1,6 @@
 #pragma once 
 
-#include "Fsm.h"
+#include <Fsm.h>
 
 // See sw-design.md for documentation
 
@@ -16,4 +16,4 @@
 
 extern Fsm powerFSM;
 
-void PowerFSM_setup();
+void PowerFSM_setup();