targets: turn on GC for TKey1 device, since it does in fact work

Signed-off-by: deadprogram <ron@hybridgroup.com>

Author: deadprogram

targets/tkey.json

@@ -7,7 +7,7 @@
  ],
  "linkerscript": "targets/tkey.ld",
  "scheduler": "none",
- "gc": "leaking",
+ "gc": "conservative",
  "flash-command": "tkey-runapp {bin}",
  "serial": "uart"
 }