fix CI build - make projectdir relative

bin/platformio-custom.py

@@ -1,16 +1,14 @@
+
+Import("projenv")
+
 import configparser
-
 config = configparser.RawConfigParser()
-config.read('version.properties')
-
+config.read(projenv["PROJECT_DIR"] + "/version.properties")
 version = dict(config.items('VERSION'))
-
 verStr = "{}.{}.{}".format(version["major"], version["minor"], version["build"])
 
 print(f"Using meshtastic platform-custom.py, firmare version {verStr}")
 
-Import("env", "projenv")
-
 # General options that are passed to the C and C++ compilers
 projenv.Append(CCFLAGS=[
     f"-DAPP_VERSION={verStr}"