[BUG] Posix operator !~ not supported on Redshift

[AlexSpannSP]

Describe the bug
Models that use the !~ operator with a redshift target will not compile

What version of dbt Fusion is this bug in? (find out by running dbt --version)
dbt-fusion 2.0.0-preview.154

Is this a discrepancy between the dbt Fusion Engine and dbt Core? Check one.

• YES
• NO

To Reproduce
Create a dbt model:

-- models/marts/negate_posix_demo.sql
SELECT 
    'a' ~ 'a',
    'b' !~ 'c'

with redshift as a target and then try to compile it:

error: dbt0101: mismatched input '!' expecting one of <EOF>, ';'
  --> models\marts\negate_posix_demo.sql:3:9 (target\compiled\models\marts\negate_posix_demo.sql:3:9)

Expected behavior
Models using the operator compile with no issues

Operating System and CPU Type (please complete the following information):

• Windows
• X86