Log Message:
lua-penlight: Update to 1.9.1

## 1.9.1 (2020-09-27)

 - fix: dir.walk [#350](https://github.com/lunarmodules/Penlight/pull/350)

## 1.9.1 (2020-09-24)

 - released to superseed the 1.9.0 version which was retagged in git after some
   distro's already had picked it up. This version is identical to 1.8.1.

## 1.8.1 (2020-09-24) (replacing a briefly released but broken 1.9.0 version)

## Fixes

  - In `pl.class`, `_init` can now be inherited from grandparent (or older \ 
ancestor) classes. [#289](https://github.com/lunarmodules/Penlight/pull/289)
  - Fixes `dir`, `lexer`, and `permute` to no longer use coroutines. \ 
[#344](https://github.com/lunarmodules/Penlight/pull/344)

## 1.8.0 (2020-08-05)

### New features

  - `pretty.debug` quickly dumps a set of values to stdout for debug purposes

### Changes

  - `pretty.write`: now also sorts non-string keys \ 
[#319](https://github.com/lunarmodules/Penlight/pull/319)
  - `stringx.count` has an extra option to allow overlapping matches
    [#326](https://github.com/lunarmodules/Penlight/pull/326)
  - added an extra changelog entry for `types.is_empty` on the 1.6.0 changelog, due
    to additional fixed behaviour not called out appropriately \ 
[#313](https://github.com/lunarmodules/Penlight/pull/313)
  - `path.packagepath` now returns a proper error message with names tried if
    it fails

### Fixes

  - Fix: `stringx.rfind` now properly works with overlapping matches
    [#314](https://github.com/lunarmodules/Penlight/pull/314)
  - Fix: `package.searchpath` (in module `pl.compat`)
    [#328](https://github.com/lunarmodules/Penlight/pull/328)
  - Fix: `path.isabs` now reports drive + relative-path as `false`, eg. \ 
"c:some/path" (Windows only)
  - Fix: OpenResty coroutines, used by `dir.dirtree`, `pl.lexer`, `pl.permute`. If
    available the original coroutine functions are now used \ 
[#329](https://github.com/lunarmodules/Penlight/pull/329)
  - Fix: in `pl.strict` also predefine global `_PROMPT2`
  - Fix: in `pl.strict` apply `tostring` to the given name, in case it is not a \ 
string.
  - Fix: the lexer would not recognize numbers without leading zero; \ 
"-.123".
    See [#315](https://github.com/lunarmodules/Penlight/issues/315)