Use Powershell to find UF2 drive if WMIC fails (#476)

Microsoft is deprecating WMIC, so fall back to a Powershell call in
case of failure to ruin WMIC.

Belt and suspenders, set PowerShell non-interactive mode and null STDIN.

tools/uf2conv.py

@@ -228,9 +228,21 @@ def to_str(b):
 def get_drives():
     drives = []
     if sys.platform == "win32":
-        r = subprocess.check_output(["wmic", "PATH", "Win32_LogicalDisk",
-                                     "get", "DeviceID,", "VolumeName,",
-                                     "FileSystem,", "DriveType"])
+        try:
+            r = subprocess.check_output(["wmic", "PATH", "Win32_LogicalDisk",
+                                         "get", "DeviceID,", "VolumeName,",
+                                         "FileSystem,", "DriveType"])
+        except:
+            try:
+                nul = open("nul:", "r")
+                r = subprocess.check_output(["powershell", "-NonInteractive", "-Command",
+                                            "Get-WmiObject -class Win32_LogicalDisk | "
+                                            "Format-Table -Property DeviceID, DriveType, Filesystem, VolumeName"],
+                                            stdin = nul)
+                nul.close()
+            except:
+                print("Unable to build drive list");
+                sys.exit(1)
         for line in to_str(r).split('\n'):
             words = re.split('\s+', line)
             if len(words) >= 3 and words[1] == "2" and words[2] == "FAT":