Log Message:
Update to alex-3.2.7.1

Change in 3.2.7.1
* Fix bug with repeated numeral characters outside of r{n,m}
  repetitions. This was a regression introduced in 3.2.7.

Changes in 3.2.7
* Allow arbitrary repetitions in regexps. Previously, the r{n,m} and
  related forms were restricted to single digit numbers n and m.
* DFA minimization used to crash on tokens of the form c* which produce
  automata with only accepting states. Considering the empty set of
  non-accepting states as an equivalence class caused minimization to crash
  with exception.
* The small_base flag is removed. Extremely old GHCs will no longer build.
* A number of bug fixes and clearer diagnostics.