app-data: Drop releases

This drops release information since it has syntax errors breaking
`ninja -C _build test`.

```
2/3 Validate appstream file                 FAIL     0.14 s (exit status 1)

--- command ---
/usr/bin/appstream-util validate --nonet data/sm.puri.Chatty.appdata.xml
--- stdout ---
data/sm.puri.Chatty.appdata.xml: FAILED:
• style-invalid         : <p> does not end in '.|:|!' [Development release]
• style-invalid         : <p> is too short [Development release]
--- stderr ---
```
3 jobs for fix-appdata in 3 minutes and 10 seconds (queued for 3 seconds)
Status Job ID Name Coverage
  Build
passed #169398
librem5
build-debian-gcc

00:01:42

 
  Test
failed #169399
librem5
test:debian-gcc

00:01:27

 
  Package
skipped #169400
librem5
build-debian-package
 
Name Stage Failure
failed
test:debian-gcc Test
--- stderr ---
Validation of files failed
-------

Full log written to /builds/guido.gunther/chatty/_build/meson-logs/testlog.txt
FAILED: meson-test
/usr/bin/meson test --no-rebuild --print-errorlogs
ninja: build stopped: subcommand failed.
ERROR: Job failed: exit code 1