message: Add missing releases to appstream manifest and fix licence
  * Add missing releases to appstream manifest
  Looks like I forgot the latest page of releases.
  * Change metadata licence to MIT
  As requested here:
  Looks like I forgot to do this.
diff: <image>https://raw.githubusercontent.com/Try/OpenGothic/master/scr0.png</image>
  </screenshot>
  </screenshots>
  - <metadata_license>CC-BY-SA-3.0</metadata_license>
  + <metadata_license>MIT</metadata_license>
  <releases>
  + <release version="0.37" date="2021-04-18"/>
  + <release version="0.36" date="2021-04-18"/>
  + <release version="0.35" date="2021-01-18"/>
  + <release version="0.34" date="2021-01-17"/>
  + <release version="0.33" date="2021-01-17"/>
  + <release version="0.32" date="2020-11-06"/>
  <release version="0.31" date="2020-10-04"/>
  <release version="0.30" date="2020-08-29"/>
  <release version="0.29" date="2020-08-27"/>
  