Merge pull request #2432 from recrof/kiss-radio-everywhere

kiss radio: added stm32 support + envs in platformio.ini

variants/nano_g2_ultra/platformio.ini

@@ -110,3 +110,8 @@ build_src_filter = ${Nano_G2_Ultra.build_src_filter}
 lib_deps = ${Nano_G2_Ultra.lib_deps}
   densaugeo/base64 @ ~1.4.0
   end2endzone/NonBlockingRTTTL@^1.3.0
+
+[env:Nano_G2_Ultra_kiss_modem]
+extends = Nano_G2_Ultra
+build_src_filter = ${Nano_G2_Ultra.build_src_filter}
+  +<../examples/kiss_modem/>