Fix deb version

[plajjan]

Finally! We now align the version contained in actonc, displayed with
actonc --version and the version of the deb package!

We compute the VERSION_INFO once and then pass it into the debian build
process to tag the inside content.

Fixes #271.

[plajjan]

Looks good!

kll@Boxy:~/Downloads$ sudo dpkg -i acton_0.6.2.20210924.16.58.23_amd64.deb 
[sudo] password for kll: 
(Reading database ... 393985 files and directories currently installed.)
Preparing to unpack acton_0.6.2.20210924.16.58.23_amd64.deb ...
Unpacking acton (0.6.2.20210924.16.58.23) over (0.6.2.20210924.14.34.31) ...
Setting up acton (0.6.2.20210924.16.58.23) ...
kll@Boxy:~/Downloads$ actonc --version
acton 0.6.2.20210924.16.58.23
compiled by ghc 8.10 on linux x86_64
cc: cc (Debian 10.2.1-6) 10.2.1 20210110
kll@Boxy:~/Downloads$ 

Merging!