[v1.18.3] Special release - pre-requisite for OTA update from 1.18.2 …

…to 1.20 Firmware

Since new Firmwares [1.20.0.xx] has increasted partition sizes and partition table structure this Intermidiate Firmware is required as 1st Step OTA to a final OTA upgrade to v1.20.0.xx from 1.18.2
before upgrading to this Firmware please see: https://docs.pycom.io/tutorials/all/ota/

[v1.20.0.rc13] Release Candidate

### Improvments
- LoRaWan refactoring and bug Fixing
- Updated Pybytes lib
- Updated sqnsupgrade
- Update Make Environment for IDF version check and checkout
- modpycom: Added API to get Internal and External Free RAM size
- PYFW-356 support for sending bytes in lte.send_at_cmd()

### Bug Fix
- Fix PYFW-359: When building SW with "BTYPE=debug" littleFS assertion fails with crash
- PYFW-348 updated rx buff size max size exception message
- PYFW-354: LittleFS causing random crash

 [v1.20.0.rc12.1] Fix wlan sta interface terminating after lte discon…

…nect (pycom#325)

* [PYFW-86] Fix wlan sta interface terminating after lte disconnect

* [v1.20.0.rc12.1] Hot fix

Fix wlan sta interface terminating after lte disconnect

* Fix compilation error

[v1.20.0.rc12] Release Candidate

### New Features
- Adding CoAp Micropython module
- Disable RGBLED functionality with Makefile switch RGB_LED=disable

### Improvments
- Updated pycom.nvs_get to support return of a predefined `NoExistValue` for unmatched Keys
- PYFW-104: Add timestamp metadata to files and folders
- Updated modlte
- [PYFW-86] Implement Fallback to Wifi when lte is disconnected
- [PYFW-214] Increase App partition Size For FIPy, GPy and LoPy4 to 1980K
- [PYFW-344] Refactor BLE
- Lorawan: Added support for the CN470 region

### Bug Fixes
- PYFW-348: Make RX buffer of machuart module configurable pycom#300

MicroPython 1.20.0.rc11.2

Add support for LoRa regions CN470 and IN865

This is a special customer pre-release and has only been tested on the LoPy4!

MicroPython 1.20.0.rc11.1 & Pybytes 0.9.12

Merge remote-tracking branch 'Dev/master' into release-candidate

[v1.18.2.r7] Firmware release

### New Features
- Esp32 touchpad functionality exposed to micropy

### Improvements
- Added RSA signature generation API to moducrypto
- Added support for saving strings in NVS - PR pycom#226 , author: @psychogenic
- LTE class refactoring

### Bug Fix
- Fix UART.sendbreak not defaulting to 13 bits as suggested by Documentation Issue pycom#280

[v1.18.2.r6] Firmware release

### Bug Fix
- Updated LTE class to fix issue in modem FW version detection.

Merge remote-tracking branch 'iwahdan/master'