Fix syntax error architecture

[Ni-Langguth]

Previously on alma10 (ignore the alma9-physical machine, this is in a docker):

[root@lcgapp-alma9-physical lcg.bits]# bits architecture
/build/nlanggut/bitsPlayground/bits/bits_helpers/sync.py:344: SyntaxWarning: invalid escape sequence '\;'
  err = execute("""\
slc10_x86-64

Now on alma10:

[root@lcgapp-alma9-physical bits]# bits architecture
slc10_x86-64

Also err was not used anywhere, as shown here:

[root@lcgapp-alma9-physical bits]# ruff check bits_helpers/sync.py
F841 Local variable `err` is assigned to but never used
   --> bits_helpers/sync.py:344:5
    |
343 |     cvmfs_architecture = re.sub(r"slc(\d+)_x86-64", r"el\1-x86_64", self.architecture)
344 |     err = execute("""\
    |     ^^^
345 |     set -x
346 |     # Exit without error in case we do not have any package published
    |
help: Remove assignment to unused variable `err`

So I added a print at the end of the function.