Quote the boot script with single quotes (#676)

Using unescaped double quotes within double quotes didn't seem to be working as expected, as I was having issues running a batch file produced from this template in a directory which contained spaces. This is similar to how it was suggested that powershell be called from a batch file here: https://stackoverflow.com/questions/19335004/how-to-run-a-powershell-script-from-a-batch-file.

priv/templates/release_rc_win_exec.eex

@@ -15,4 +15,4 @@ where pwsh >nul 2>nul
 if %ERRORLEVEL% equ 0 (
   set prog=pwsh
 )
-%prog% -NonInteractive -NoProfile -ExecutionPolicy Bypass -Command "& "%boot_script%" @args" %*
+%prog% -NonInteractive -NoProfile -ExecutionPolicy Bypass -Command "& '%boot_script%' @args" %*