Include `diffstat` in the dependencies

[zhassan-aws]

I installed the tool using sudo apt install bmt, but when I ran cpbm update, it errored out because of a missing diffstat command:

$ cpbm update ../bmark_suite1.tar.gz 
/usr/bin/make -f /usr/share/bmt/rules.cpbm.generic clean
make[1]: Entering directory '/home/ubuntu/examples/bmt/kani/bmark_suite1-foo'
test -d cprover
rm -rf results.* build
rm -f cprover/binaries.* cprover/verified.*
rm -rf cprover/results.*
make[1]: Leaving directory '/home/ubuntu/examples/bmt/kani/bmark_suite1-foo'
Added patch bmark_suite1-foo/cprover/patches/001-new_patch.qBJwd2 to record the following changes:
/usr/share/bmt/update.sh: line 191: diffstat: command not found

Installing diffstat using sudo apt install diffstat resolved the issue, but is it possible to include it in the Debian package dependencies?