Move upper bounds back to 2.0

[emmyoop]

Problem

The upper bound pin of dbt-common and dbt-adapters is causing adapters to pick up the wrong, older version, of dbt-core.

Solution

Open the pin of dbt-common and dbt-adapters back up to 2.0 on 1.8.latest.

Checklist

• I have read the contributing guide and understand what's expected of me.
• I have run this code in development, and it appears to resolve the stated issue.
• This PR includes tests, or tests are not required or relevant for this PR.
• This PR has no interface changes (e.g., macros, CLI, logs, JSON artifacts, config files, adapter interface, etc.) or this PR has already received feedback and approval from Product or DX.
• This PR includes type annotations for new and modified functions.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 88.27%. Comparing base (3a1c605) to head (4c98df3).
Report is 1 commits behind head on 1.8.latest.

Additional details and impacted files

@@              Coverage Diff               @@
##           1.8.latest   #11024      +/-   ##
==============================================
- Coverage       88.33%   88.27%   -0.06%     
==============================================
  Files             181      181              
  Lines           22796    22796              
==============================================
- Hits            20136    20123      -13     
- Misses           2660     2673      +13     

Flag	Coverage Δ
integration	85.45% <ø> (-0.14%)	⬇️
unit	62.83% <ø> (ø)

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