fix: correct ADVERT_NAME for ThinkNode M5 (was M2)

Repeater and Room Server environments in variants/thinknode_m5/platformio.ini
were using 'Thinknode M2' as the ADVERT_NAME, causing M5 nodes to advertise
with the wrong device name on the mesh.

- env:ThinkNode_M5_Repeater: 'Thinknode M2 Repeater' -> 'Thinknode M5 Repeater'
- env:ThinkNode_M5_room_server: 'Thinknode M2 Room Server' -> 'Thinknode M5 Room Server'

variants/thinknode_m5/platformio.ini

@@ -58,7 +58,7 @@ build_src_filter = ${ThinkNode_M5.build_src_filter}
   +<../examples/simple_repeater/*.cpp>
 build_flags =
   ${ThinkNode_M5.build_flags}
-  -D ADVERT_NAME='"Thinknode M2 Repeater"'
+  -D ADVERT_NAME='"Thinknode M5 Repeater"'
   -D ADVERT_LAT=0.0
   -D ADVERT_LON=0.0
   -D ADMIN_PASSWORD='"password"'
@@ -116,7 +116,7 @@ build_src_filter = ${ThinkNode_M5.build_src_filter}
   +<../examples/simple_room_server>
 build_flags =
   ${ThinkNode_M5.build_flags}
-  -D ADVERT_NAME='"Thinknode M2 Room Server"'
+  -D ADVERT_NAME='"Thinknode M5 Room Server"'
   -D ADVERT_LAT=0.0
   -D ADVERT_LON=0.0
   -D ADMIN_PASSWORD='"password"'