fix(ingest): restrict snowflake's sqlalchemy dep

[hsheth2]

Related to snowflakedb/snowflake-sqlalchemy#350.

Checklist

• The PR conforms to DataHub's Contributing Guideline (particularly Commit Message Format)
• Links to related issues (if applicable)
• Tests for the changes have been added/updated (if applicable)
• Docs related to the changes have been added/updated (if applicable). If a new feature has been added a Usage Guide has been added for the same.
• For any breaking change/potential downtime/deprecation/big changes an entry has been made in Updating DataHub

[github-actions]

Unit Test Results (metadata ingestion)

       8 files  ±  0         8 suites  ±0   1h 1m 18s ⏱️ -7s
   765 tests  -   2     763 ✔️ +  1  2 💤 ±0  0 ❌  - 1 
1 532 runs  +22  1 527 ✔️ +31  5 💤 ±0  0 ❌  - 1 

Results for commit 4da10cf. ± Comparison against base commit 329ecb8.

This pull request removes 2 tests.

tests.unit.test_snowflake_beta_source
tests.unit.test_snowflake_source

[github-actions]

Unit Test Results (build & test)

621 tests  ±0   617 ✔️ ±0   15m 37s ⏱️ -20s
157 suites ±0       4 💤 ±0 
157 files   ±0       0 ❌ ±0 

Results for commit 4da10cf. ± Comparison against base commit 329ecb8.

[treff7es]

lgtm