Re-enable STM32F1 Travis test (#13978)

.travis.yml

   - TEST_PLATFORM="DUE"
   - TEST_PLATFORM="LPC1768"
   - TEST_PLATFORM="LPC1769"
-  #- TEST_PLATFORM="STM32F1"
+  - TEST_PLATFORM="STM32F1"
   - TEST_PLATFORM="teensy35"
   - TEST_PLATFORM="linux_native"
   - TEST_PLATFORM="esp32"

buildroot/share/tests/STM32F1-tests

 restore_configs
 opt_set MOTHERBOARD BOARD_STM32F1R
 opt_set EXTRUDERS 2
+opt_set SERIAL_PORT -1
 opt_enable EEPROM_SETTINGS EEPROM_CHITCHAT REPRAP_DISCOUNT_SMART_CONTROLLER SDSUPPORT \
            PAREN_COMMENTS GCODE_MOTION_MODES SINGLENOZZLE TOOLCHANGE_FILAMENT_SWAP TOOLCHANGE_PARK \
-           GCODE_MACROS
+           GCODE_MACROS NOZZLE_PARK_FEATURE NOZZLE_CLEAN_FEATURE
 exec_test $1 $2 "STM32F1R EEPROM_SETTINGS EEPROM_CHITCHAT REPRAP_DISCOUNT_SMART_CONTROLLER SDSUPPORT PAREN_COMMENTS GCODE_MOTION_MODES"
 
 # cleanup

platformio.ini

 # STM32F103RE
 #
 [env:STM32F1]
-platform      = ststm32@<4.4.0
+platform      = ststm32
 framework     = arduino
 board         = genericSTM32F103RE
 build_flags   = !python Marlin/src/HAL/HAL_STM32F1/STM32F1_flag_script.py