Default back to tbeam in builds, so it will work for others

platformio.ini

@@ -9,7 +9,7 @@
 ; https://docs.platformio.org/page/projectconf.html
 
 [platformio]
-default_envs = rak815 ; Note: the github actions CI test build can't yet build NRF52 targets
+default_envs = tbeam ; Note: the github actions CI test build can't yet build NRF52 targets
 
 [common]
 ; common is not currently used