Do not astyle-check mbed-coap which is imported

LDong-Arm · LDong-Arm · commit 7927ccd0f835 · 2020-07-16T17:06:57.000+01:00
diff --git a/.astyleignore b/.astyleignore
@@ -1,5 +1,6 @@
 ^BUILD
 ^cmsis
+^connectivity/libraries/mbed-coap
 ^features/cryptocell
 ^features/FEATURE_BLE
 ^features/FEATURE_EXPERIMENTAL_API/FEATURE_PSA/TARGET_MBED_PSA_SRV
