Simpler version for AppImage and branch name in the continuous release

The command `git rev-parse --abbrev-ref HEAD` is not returning the branch name
in the travis server, and for the version in AppImage filename it would be
enough to have the short commit id.

Note that these changes are branch dependant.

See issue sqlitebrowser#1092

Author: mgrojo

.travis.yml

@@ -60,15 +60,15 @@ script:
 - cd ..
 - wget -c -nv "https://github.com/probonopd/linuxdeployqt/releases/download/6/linuxdeployqt-6-x86_64.AppImage"
 - chmod a+x linuxdeployqt-6-x86_64.AppImage
-- export VERSION=$(printf "`git rev-parse --abbrev-ref HEAD`-`git rev-list HEAD --count`-` git -C . rev-parse --short HEAD`")    #$(git rev-parse --short HEAD) # linuxdeployqt uses this for naming the file
+- export VERSION=`git -C . rev-parse --short HEAD` # linuxdeployqt uses this for naming the file
 - ./linuxdeployqt-6-x86_64.AppImage appdir/usr/share/applications/*.desktop -appimage
 
 
 after_success:
   - find appdir -executable -type f -exec ldd {} \; | grep " => /usr" | cut -d " " -f 2-3 | sort | uniq
   - wget -c https://github.com/probonopd/uploadtool/raw/master/upload.sh
   - chmod a+x upload.sh
-  - UPLOADTOOL_ISPRERELEASE=true UPLOADTOOL_SUFFIX=$VERSION ./upload.sh DB_Browser_for_SQLite*.AppImage*
+  - UPLOADTOOL_ISPRERELEASE=true UPLOADTOOL_SUFFIX=v3.12.x ./upload.sh DB_Browser_for_SQLite*.AppImage*
 
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