Fix path in Debian md5sums file

[Flood1993]

When packaging a Debian file, I noticed:

$ cat /var/lib/dpkg/info/<my-pkg>.md5sums
d53cafdbafeaa62df89f21a80ccb7c1e  ./etc/<my-pkg>/<some-file>.yml

From the Debian md5sums manpages:

This file contains a list of MD5 digests (as 32 case-insensitive
hexadecimal characters) followed by two spaces (U+0020 SPACE) and
the absolute pathname of a plain file, one per line.

Trailing slashes (U+002F /) in the pathname will be trimmed.
Neither trailing whitespace nor empty or whitespace-only
lines are accepted.

So, a proper file should contain lines like (note no ./):

d53cafdbafeaa62df89f21a80ccb7c1e  etc/<my-pkg>/<some-file>.yml

I do not know Go but I was able to come up with this fix which works at least for my use case.

[codecov]

Codecov Report

❌ Patch coverage is 0% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 73.05%. Comparing base (532c31d) to head (ba95f3e).
⚠️ Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
deb/deb.go	0.00%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1052   +/-   ##
=======================================
  Coverage   73.05%   73.05%           
=======================================
  Files          22       22           
  Lines        2576     2576           
=======================================
  Hits         1882     1882           
  Misses        480      480           
  Partials      214      214           

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[caarlos0]

thanks!