Fix failure to save settings on Windows

[NHellFire]

Description:

Saving settings on Windows fails with:

Traceback (most recent call last):
  File "C:\Users\Nathan\.pyenv\pyenv-win\versions\3.11.3\Lib\shutil.py", line 825, in move
    os.rename(src, real_dst)
PermissionError: [WinError 32] The process cannot access the file because it is being used by another process: 'C:\\Users\\Nathan\\.local\\apprise-api\\apprise_api\\var\\config\\27\\tmpi0utrc0z.tmp' -> 'C:\\Users\\Nathan\\.local\\apprise-api\\apprise_api\\var\\config\\27\\7a415748edb692e8bf8c4361e9777d92f2dfad2359bbd8c9fbcd49.text'

mkstemp() also returns an open file handle (that we don't use), which must be closed as Windows won't allow renaming an open file.

Checklist

• [X] The code change is tested and works locally.
• [X] There is no commented out code in this PR.
• [X] No lint errors (use flake8)
• [X] Tests added

[caronc]

This was educational for me. I didn't realize the handle had to be closed in this circumstance. Thank you!