[cragr] Stricter matching patterns for rdates

Somme patterns for matching rdates from transactions labels
weren't strict enough, for exemple :

^(?P<category>PRELEVEMENT) (?P<text>.*) (?P<dd>\d{2})\s(?P<mm>\d{2})\s(?P<yy>\d{4}) .*
matched PRELEVEMENT TEXT TEXT (YYYY MM DD YYYY MM DD)

^(?P<category>PRELEVEMENT) (?P<text>.*) (?P<dd>\d{2})-(?P<mm>\d{2})$
matched PRELEVEMENT TEXT TEXT MM-YY

Both were made stricter as to avoid these unwanted matches that would
crash the date parser.