Change esptool.py -> esptool

Current preferred practice seems to be to use the name esptool for the
command, not esptool.py.

Makefile

@@ -12,7 +12,7 @@ MAX80_IP  ?= max80.local
 CURL	   = curl
 PERL	   = perl
 PYTHON     = python
-ESPTOOL   ?= esptool.py
+ESPTOOL   ?= esptool
 export ESPTOOL
 
 all clean spotless :

tools/flashmax.pl

@@ -9,7 +9,7 @@ use Time::HiRes qw(usleep tv_interval);
 use Digest::CRC qw(crc32);
 use v5.10;			# For "state"
 
-my $esptool = 'esptool.py';
+my $esptool = 'esptool';
 $esptool = $ENV{'ESPTOOL'} || $esptool;
 
 my $esp_retries = 10;
@@ -25,7 +25,7 @@ my %datatypes = (
     'fpgainit'  => 5,		# FPGA bypass (transient) image during update
     'esppart'   => 6,		# ESP32 partition table
     'espsys'    => 7,		# ESP32 boot loader, OTA control partition...
-    'esptool'   => 8,		# esptool.py options for flashing
+    'esptool'   => 8,		# esptool options for flashing
     'boardinfo' => 9		# board_info base address
     );
 my @type;