Change WORKDIR from / to /usr/src/app

What changed is that in bookworm the lib dir has become a symlink to /usr/lib.
This prevents `COPY . .` to copy over our lib dir to the layer.

For more information:
* https://wiki.debian.org/NewInBookworm
* https://wiki.debian.org/UsrMerge
* https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=978636:

Closes: Perl#140

Signed-off-by: Wesley Schwengle <waterkip@cpan.org>

Author: waterkip

generate.pl

@@ -318,6 +318,6 @@ =head1 DESCRIPTION
     && rm -fr /root/.cpanm /usr/src/perl /usr/src/{{cpanm_dist_name}}* /tmp/* \
     && cpanm --version && cpm --version
 
-WORKDIR /
+WORKDIR /usr/src/app
 
 CMD ["perl{{version}}","-de0"]