Bug 28707: Translate RECEIPT notice

Bug 28707: Translate RECEIPT notice

There is a badly crafted regex used when extracting
strings in multiline fields in yaml files
The regex is my own, introduced in Bug 24262, sorry.

This patch correct it a little. Better eyes are welcome.

To test:
1) go to misc translator, update some language
    ./translate update fr-CA

2) check missing strings

    egrep "Total out|Operator ID|August 31" po/fr-CA-installer.po

   first two are from sample notices, third from sample creator data

3) apply the patch, repeat 1)

4) repeat 2), verify the strings are present in the translation file

5) translate some of the new strings, install the language,
   verify strings are present in the translated files
    ./translate install fr-CA
   check fr-CA/optional/sample_creator_data.yml and
   fr-CA/mandatory/sample_notices.yml

There are some 60+ new strings.

Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>