.github/workflows: Add ICU4C to places where we build and test doltgresql.

[reltuk]

No description provided.

[github-actions]

	Main	PR
covering_index_scan_postgres	325.21/s	325.90/s	+0.2%
index_join_postgres	154.45/s	153.86/s	-0.4%
index_join_scan_postgres	193.54/s	192.65/s	-0.5%
index_scan_postgres	12.19/s	12.18/s	-0.1%
oltp_point_select	2534.70/s	2504.59/s	-1.2%
oltp_read_only	1828.08/s	1825.35/s	-0.2%
select_random_points	116.52/s	118.61/s	+1.7%
select_random_ranges	128.20/s	132.28/s	+3.1%
table_scan_postgres	11.58/s	11.62/s	+0.3%
types_table_scan_postgres	5.36/s	5.46/s	+1.8%

[github-actions]

	Main	PR
Total	42090	42090
Successful	16828	16828
Failures	25262	25262
Partial Successes1	5552	5552

	Main	PR
Successful	39.9810%	39.9810%
Failures	60.0190%	60.0190%

Footnotes

1. These are tests that we're marking as Successful, however they do not match the expected output in some way. This is due to small differences, such as different wording on the error messages, or the column names being incorrect while the data itself is correct. ↩