Attempt fixing GitHub actions ESP8266 build (#3151)

(explicit toolchain version)

platformio.ini

@@ -66,7 +66,7 @@ platform_wled_default = ${common.arduino_core_4_1_0}
 # We use 2.7.4.7 for all, includes PWM flicker fix and Wstring optimization
 #platform_packages = tasmota/framework-arduinoespressif8266 @ 3.20704.7
 platform_packages = platformio/framework-arduinoespressif8266
-                    platformio/toolchain-xtensa #@ ~2.40802.200502
+                    platformio/toolchain-xtensa @ ~2.100300.220621 #2.40802.200502
                     platformio/tool-esptool #@ ~1.413.0
                     platformio/tool-esptoolpy #@ ~1.30000.0