[ufotools] cannot handle global guidelines

[frankrolf]

makeotf v 2.6.0 fails for a UFO3 file with global guidelines:

Traceback (most recent call last):
  File "/usr/local/bin/makeotf", line 11, in <module>
    sys.exit(main())
  File "/usr/local/lib/python3.7/site-packages/afdko/makeotf.py", line 2684, in main
    setMissingParams(makeOTFParams)
  File "/usr/local/lib/python3.7/site-packages/afdko/makeotf.py", line 1791, in setMissingParams
    ufo_fmndb_path = ufotools.makeUFOFMNDB(srcFontPath)
  File "/usr/local/lib/python3.7/site-packages/afdko/ufotools.py", line 2492, in makeUFOFMNDB
    fiMap, fiList = parsePList(fontInfoPath)
  File "/usr/local/lib/python3.7/site-packages/afdko/ufotools.py", line 1261, in parsePList
    (listChild.tag, child.tag, lastName, filePath))
afdko.ufotools.UFOParseError: In plist file, encountered unhandled key type 'dict' in 'array' for parent key guidelines. /Users/fgriessh/Desktop/guideline_test/guideline_test.ufo/fontinfo.plist.

This is one of the issues encountered with UFO files submitted by @rbmntjs.
Example single-glyph UFO attached.

guideline_test.ufo.zip