chore: bump mysqlclient version

[gnought]

SUMMARY

MySQLClient 1.4.2post1 is quite old, and it's time to update to fix bugs.
v2.1.0 supports multiple statements in default. We could issue set @T=1; select @T; when Allow DML is true.
The change log could refer to https://github.com/PyMySQL/mysqlclient/blob/main/HISTORY.rst

BEFORE/AFTER SCREENSHOTS OR ANIMATED GIF

TESTING INSTRUCTIONS

ADDITIONAL INFORMATION

• Has associated issue:
• Required feature flags:
• Changes UI
• Includes DB Migration (follow approval process in SIP-59)
  • Migration is atomic, supports rollback & is backwards-compatible
  • Confirm DB migration upgrade and downgrade tested
  • Runtime estimates and downtime expectations provided
• Introduces new feature or API
• Removes existing feature or API

[codecov]

Codecov Report

Merging #17556 (f57884a) into master (7429282) will increase coverage by 0.00%.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master   #17556   +/-   ##
=======================================
  Coverage   76.95%   76.96%           
=======================================
  Files        1049     1049           
  Lines       56671    56681   +10     
  Branches     7851     7851           
=======================================
+ Hits        43611    43622   +11     
+ Misses      12807    12806    -1     
  Partials      253      253           

Flag	Coverage Δ
hive	81.61% <ø> (+<0.01%)	⬆️
mysql	82.02% <ø> (+<0.01%)	⬆️
postgres	82.03% <ø> (+<0.01%)	⬆️
python	82.38% <ø> (+<0.01%)	⬆️
sqlite	81.71% <ø> (+<0.01%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
superset/cli.py	54.82% <0.00%> (-0.11%)	⬇️
superset/constants.py	100.00% <0.00%> (ø)
superset/datasets/api.py	91.03% <0.00%> (+0.89%)	⬆️
superset/db_engine_specs/trino.py	63.85% <0.00%> (+4.13%)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 7429282...f57884a. Read the comment docs.

[villebro]

@gnought can you add some context in the description why the bump is needed.

[villebro]

@gnought thanks for adding context to the description 👍 I hadn't noticed we had conflicting versions of mysqlclient on setup.py and requirements/development.(in|txt). As I see some removals/deprecations on the 2.x version, It could be a good idea to add a note to UPDATING.md to make sure people/orgs that are currently running the 1.x version make sure they make any necessary changes to their connection configs.

[villebro]

LGTM