xml: use last_child() to check for Chars

We have access to the last child directy, so we can simplify
the code.
7 jobs for tree in 27 minutes and 35 seconds (queued for 2 seconds)
latest
Status Job ID Name Coverage
  Test
passed #296683
fedora test

00:07:33

 
  Lint
manual #296685
allowed to fail manual
clippy
manual #296684
allowed to fail manual
rustfmt
passed #296686
tarball

00:12:16

 
  Cross Distro
failed #296689
debian_i386:testing

00:01:44

failed #296688
allowed to fail
debian:testing

00:01:41

passed #296687
allowed to fail
fedora:rawhide

00:07:45

 
Name Stage Failure
failed
debian_i386:testing Cross Distro
make[2]: *** [Makefile:1904: /builds/pborelli/librsvg/_build/target/debug/librsvg_internals.a] Segmentation fault (core dumped)
make[1]: *** [Makefile:1416: all-recursive] Error 1
make[1]: Leaving directory '/builds/pborelli/librsvg/_build'
make: *** [Makefile:956: all] Error 2
Uploading artifacts...
WARNING: _build/tests/*.log: no matching files
WARNING: _build/tests/output/: no matching files
ERROR: No files to upload
ERROR: Job failed: exit code 1
failed
debian:testing Cross Distro
make[2]: Leaving directory '/builds/pborelli/librsvg/_build'
make[1]: *** [Makefile:1416: all-recursive] Error 1
make[1]: Leaving directory '/builds/pborelli/librsvg/_build'
make: *** [Makefile:956: all] Error 2
Uploading artifacts...
WARNING: _build/tests/*.log: no matching files
WARNING: _build/tests/output/: no matching files
ERROR: No files to upload
ERROR: Job failed: exit code 1