message: Fix key/value highlighting in bib files
  This closes
diff: <key>1</key>
  <dict>
  <key>name</key>
  - <string>string.unquoted.key.bibtex</string>
  + <string>support.variable.key.bibtex</string>
  </dict>
  <key>2</key>
  <dict>
  <key>1</key>
  <dict>
  <key>name</key>
  - <string>string.unquoted.key.bibtex</string>
  + <string>support.variable.key.bibtex</string>
  </dict>
  <key>2</key>
  <dict>
  <string>punctuation.definition.string.end.bibtex</string>
  </dict>
  </dict>
  - <key>name</key>
  - <string>string.quoted.other.braces.bibtex</string>
  <key>patterns</key>
  <array>
  <dict>
  