deps: update icu to include tzdata2020a

[codebytere]

Closes nodejs/Release#576.

Updates source/data/in/icudt66l.dat file with updated binary time zone data files corresponding to new IANA tzdata releases in unicode-org/icu@a951ab5.

I followed the steps in #30364, but as i have not done this before I'd appreciate a confirmation that i did it correctly if possible.

cc @apaprocki @targos @srl295

Checklist

• make -j4 test (UNIX), or vcbuild test (Windows) passes
• commit message follows commit guidelines

[codebytere]

@srl295 @targos rebased and updated, PTAL when you can!

[srl295]

@codebytere thanks, i am testing it now..

[srl295]

By the way: I landed #30364 thanks @apaprocki

[srl295]

LGTM

> process.versions.tz
'2020a'

and also:

# Node v12.16.3
$ env TZ='Africa/Casablanca' node -p "new Date('2020-05-26T00:00:00.000Z').toLocaleString()"
5/26/2020, 1:00:00 AM

# this PR
$ env TZ='Africa/Casablanca' ./out/Release/node -p "new Date('2020-05-26T00:00:00.000Z').toLocaleString()"
5/26/2020, 12:00:00 AM

[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/31409/

[srl295]

failures don't seem relevant, but not sure.

21:32:17   ...
21:32:17 ok 3010 pseudo-tty/test-tty-wrap
21:32:17   ---
21:32:17   duration_ms: 0.151
21:32:17   ...
21:32:17 make[1]: *** [Makefile:532: test-ci] Error 1
21:32:17 make: *** [Makefile:561: run-ci] Error 2
21:32:17 Build step 'Conditional steps (multiple)' marked build as failure
21:32:17 All downstream projects complete!
21:32:17 Performing Post build task...
21:32:17 Match found for : : True

[codebytere]

@srl295 it's not related - it's an issue caused by a buildflag interacting with this commit

[codebytere]

Landed in ed9be3a

[targos]

This will need a backport to land on v12.x