Upgrade to regex-compat-tdfa to squelch Unicode problems

regex-compat is notoriously poor at supporting non-ASCII character sets. I have a UTF-8 encoded .csv file containing Unicode (a Unicode pound sign, in particular) and this seemed to cause hledger some difficulties:

    $ hledger print --rules-file "Paypal.rules" -f "Paypal.csv"
    using conversion rules file /Users/mbolingbroke/Dropbox/Finances/ledger/Paypal.rules
    hledger: user error (Text.Regex.Posix.String died: (ReturnCode 17,"illegal byte sequence"))

After recompiling hledger-lib/hledger with regex-compat-tdfa instead, this was solved painlessly:

    $ hledger print --rules-file "Paypal.rules" -f "Paypal.csv"
    using conversion rules file /Users/mbolingbroke/Dropbox/Finances/ledger/Paypal.rules