Ensure makeboards.py writes UNIX newlines (#2264)

The repo and development use only '\n' (UNIX) EOLs.  When a user runs
makeboards on a Windows system they end up changing every line in boards.txt
and the JSON files to Windows '\r\n' format.

Explicitly set the newline character when opening the output files to
avoid this.

Author: earlephilhower

tools/makeboards.py

@@ -356,14 +356,14 @@ def MakeBoardJSON(name, vendor_name, product_name, vid, pid, pwr, boarddefine, f
 .replace('USBPWR', str(pwr))\
 .replace(' EXTRA_INFO', m_extra.rstrip())
     jsondir = os.path.abspath(os.path.dirname(__file__)) + "/json"
-    f = open(jsondir + "/" + name + ".json", "w")
+    f = open(jsondir + "/" + name + ".json", "w", newline='\n')
     f.write(json)
     f.close()
 
 pkgjson = json.load(open(os.path.abspath(os.path.dirname(__file__)) + '/../package/package_pico_index.template.json'))
 pkgjson['packages'][0]['platforms'][0]['boards'] = []
 
-sys.stdout = open(os.path.abspath(os.path.dirname(__file__)) + "/../boards.txt", "w")
+sys.stdout = open(os.path.abspath(os.path.dirname(__file__)) + "/../boards.txt", "w", newline='\n')
 WriteWarning()
 BuildGlobalMenuList()
 
@@ -530,5 +530,5 @@ def MakeBoardJSON(name, vendor_name, product_name, vid, pid, pwr, boarddefine, f
 MakeBoard("generic", "Generic", "RP2040", "0x2e8a", "0xf00a", 250, "GENERIC_RP2040", 16, "boot2_generic_03h_4_padded_checksum")
 
 sys.stdout.close()
-with open(os.path.abspath(os.path.dirname(__file__)) + '/../package/package_pico_index.template.json', 'w') as f:
+with open(os.path.abspath(os.path.dirname(__file__)) + '/../package/package_pico_index.template.json', 'w', newline='\n') as f:
     f.write(json.dumps(pkgjson, indent=3))