[ESP32] Revert back to Espressif32 PIO v 2.1.0 due to serial issues

When calling Serial::begin() (on ESP32) you apparently need to give all parameters or else it may use default parameters (makes no sense!)
Serial::end() may cause a hang or crash -> timing issue

See crash/hang:
- espressif/arduino-esp32#5047
- espressif/arduino-esp32#5004
- espressif/arduino-esp32@81b7c47
- espressif/arduino-esp32#5112
- espressif/arduino-esp32#5032

Switch back to default:
- espressif/arduino-esp32#5026

Author: TD-er

platformio_core_defs.ini

@@ -139,6 +139,9 @@ platform_packages =
 [core_esp32_1_12_2]
 platform                  = [email protected]
 
+[core_esp32_2_1_0]
+platform                  = [email protected]
+
 [core_esp32_3_2_0]
 platform                  = [email protected]
 

platformio_esp32_envs.ini

@@ -7,7 +7,7 @@
 
 
 [esp32_common]
-extends                   = common, core_esp32_3_2_0
+extends                   = common, core_esp32_2_1_0
 lib_ignore                = ESP8266WiFi, ESP8266Ping, ESP8266WebServer, ESP8266HTTPUpdateServer, ESP8266mDNS, IRremoteESP8266, ESPEasy_ESP8266Ping, ESP32_ping, HeatpumpIR
 lib_deps                  = https://github.com/TD-er/ESPEasySerial.git#v2.0.5, adafruit/Adafruit ILI9341 @ ^1.5.6,  Adafruit GFX Library, LOLIN_EPD, Adafruit BusIO, VL53L0X @ 1.3.0, SparkFun VL53L1X 4m Laser Distance Sensor @ 1.2.9
 board_build.f_flash       = 80000000L