UFO groups.plist has extra characters

[mgavioli]

In both OFLGoudyStM.ufo and OFLGoudyStM-Italic.ufo, the file groups.plist has an extra apostrophe (') at the end of the first string of each <array>.

For instance the first <dict> entry of OFLGoudyStM.ufo reads:
<key>@MMK_L_A</key>
  <array>
      <string>A'</string>
      <string>Aacute</string>
      ...
  </array>
<key>@MMK_L_A.c2</key>

where it should read:

<key>@MMK_L_A</key>
  <array>
      <string>A</string>
      <string>Aacute</string>
      ...
  </array>
<key>@MMK_L_A.c2</key>

This makes the file invalid (in some contexts? I tested it with FontForge).

I can provide a PR, if there is any chance it would be merged...