[v1.18.2.r4] Firmware release

### Improvements:
- Releasing GIL when ssl handshake is performed.
- Allow PDN list update when carrier is defined in LTE
- Add support for LTE modem responses greater than UART buff size
- Added Check for LTE band support against both SW and HW versions of the LTE modem.
- Updated Sqns upgrade scripts to v1.2.5
### Bug Fixes:
- Enabling Access to 2nd SPI perf for GPY modules
- Use Hardware timers for Lora timer tick to fix RTOS timer drifts when cache is disabled.

Author: iwahdan88

esp32/pycom_version.h

@@ -10,7 +10,7 @@
 #ifndef VERSION_H_
 #define VERSION_H_
 
-#define SW_VERSION_NUMBER                              "1.18.2.r3"
+#define SW_VERSION_NUMBER                              "1.18.2.r4"
 
 #define LORAWAN_VERSION_NUMBER                         "1.0.2"