Fix case-insensitive ESPDuino file name
Fix case-insensitive ESPDuino file name

I work on Linux and I got an error about a missing `pins_arduino.h`:
```
fatal error: pins_arduino.h: No such file or directory
```
As it turns out, the reason for this is that the directory name under Linux is case-sensitive while it is lowercase-only in the variants file.
jes/Arduino,Adam5Wu/Arduino,hallard/Arduino,Adam5Wu/Arduino,me-no-dev/Arduino,wemos/Arduino,NullMedia/Arduino,jes/Arduino,lrmoreno007/Arduino,Juppit/Arduino,hallard/Arduino,toastedcode/esp8266-Arduino,Links2004/Arduino,me-no-dev/Arduino,quertenmont/Arduino,sticilface/Arduino,sticilface/Arduino,Adam5Wu/Arduino,Links2004/Arduino,wemos/Arduino,martinayotte/ESP8266-Arduino,lrmoreno007/Arduino,me-no-dev/Arduino,lrmoreno007/Arduino,NullMedia/Arduino,Links2004/Arduino,quertenmont/Arduino,NullMedia/Arduino,Lan-Hekary/Arduino,KaloNK/Arduino,wemos/Arduino,Adam5Wu/Arduino,KaloNK/Arduino,Juppit/Arduino,wemos/Arduino,quertenmont/Arduino,Juppit/Arduino,KaloNK/Arduino,hallard/Arduino,lrmoreno007/Arduino,toastedcode/esp8266-Arduino,Lan-Hekary/Arduino,martinayotte/ESP8266-Arduino,me-no-dev/Arduino,hallard/Arduino,toastedcode/esp8266-Arduino,gguuss/Arduino,sticilface/Arduino,KaloNK/Arduino,jes/Arduino,me-no-dev/Arduino,lrmoreno007/Arduino,jes/Arduino,quertenmont/Arduino,Lan-Hekary/Arduino,sticilface/Arduino,NullMedia/Arduino,martinayotte/ESP8266-Arduino,gguuss/Arduino,Links2004/Arduino,Juppit/Arduino,jes/Arduino,esp8266/Arduino,sticilface/Arduino,quertenmont/Arduino,martinayotte/ESP8266-Arduino,Lan-Hekary/Arduino,gguuss/Arduino,esp8266/Arduino,Links2004/Arduino,hallard/Arduino,gguuss/Arduino,Juppit/Arduino,Adam5Wu/Arduino,Lan-Hekary/Arduino,esp8266/Arduino,esp8266/Arduino,toastedcode/esp8266-Arduino,esp8266/Arduino,toastedcode/esp8266-Arduino,gguuss/Arduino,NullMedia/Arduino,KaloNK/Arduino,martinayotte/ESP8266-Arduino,wemos/Arduino