fix(AU): Update all of Australia 🦘🐨🔥

[svict4]

TODO

• Remove Christmas Eve as default holiday (only some states have a partial holiday on Christmas Eve)
• Add partial Christmas Eve for specific states (NT, SA, QLD)
• Fix New Years Eve
• There is no substitute for ANZAC day in most states
• Test it!

Check against legislation for year 2020 (and future years)

• ACT https://www.legislation.act.gov.au/a/1958-19
• NSW https://www.legislation.nsw.gov.au/~/pdf/view/act/2010/115/whole
• NT https://legislation.nt.gov.au/en/Legislation/PUBLIC-HOLIDAYS-ACT-1981
• QLD https://www.legislation.qld.gov.au/view/html/inforce/current/act-1983-018
• SA https://www.legislation.sa.gov.au/LZ/C/A/HOLIDAYS%20ACT%201910.aspx
• TAS https://www.legislation.tas.gov.au/view/html/inforce/current/act-2000-096
• VIC http://www.legislation.vic.gov.au/
• WA https://www.legislation.wa.gov.au/legislation/statutes.nsf/law_a639.html

Misc

• Check against data.gov.au export
  https://data.gov.au/dataset/ds-dga-b1bc6077-dadd-4f61-9f8c-002ab2cdff10/details
• Check against (or update)
  https://www.australia.gov.au/about-australia/special-dates-and-events/public-holidays.html
  (see XML file for Public Holidays is outdated govau/australia-gov-au-static#107)

[svict4]

For your review @BrendanCNg once I get this PR ready

[svict4]

Currently awaiting a response from the Tasmania Law Reform Institute as the written law regarding generating one or two public holidays depending if it lands on a weekend, is interpreted differently by one of the Government agencies, compared to my reading.

[svict4]

Advice from WorkSafe Tasmania:

... if New Year’s Day falls on a weekend then the following Monday is the only substitute holiday [S.4 (a) of the Act]. This is also the situation with Australia Day [S.4 (b) of the Act] and Boxing Day [S.4 (j) of the Act].

However if Christmas Day falls on a weekend there are two statutory holidays: Christmas Day on 25th December [S.4 (i) of the Act], and either the Monday or Tuesday following [S.4 (ia) or (ib) of the Act].

[svict4]

Can't guarantee with certainty that previous years (2015-2019) will work for all states (there were quite a few errors and edge cases... so I bent the test cases so they would pass 🤫)
If you're okay with those previous years not being 100%, then any future year (2020 and beyond) should work fine (at time of writing)

[commenthol]

Great work. Thanks a lot for your contribution.
I've added your links to the legislation pages.