fix: keep old names from screenshot images to pypi releases

[dpgaspar]

SUMMARY

Partially fixes broken images links on Pypi: https://pypi.org/project/apache-superset/

Note same effect on 1.0 branch: https://github.com/apache/superset/tree/1.0

Some images do not render on Pypi because we need to access the raw path on github:
pypi/warehouse#5246

These images were renamed after the 1.0.0 cut. We should think about a way to support these links for a certain period of time

TEST PLAN

ADDITIONAL INFORMATION

• Has associated issue:
• Changes UI
• Requires DB Migration.
• Confirm DB Migration upgrade and downgrade tested.
• Introduces new feature or API
• Removes existing feature or API

[codecov-io]

Codecov Report

Merging #12664 (5dd3f86) into master (734fb75) will decrease coverage by 3.44%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master   #12664      +/-   ##
==========================================
- Coverage   66.85%   63.40%   -3.45%     
==========================================
  Files        1018      488     -530     
  Lines       49776    30115   -19661     
  Branches     4869        0    -4869     
==========================================
- Hits        33278    19095   -14183     
+ Misses      16375    11020    -5355     
+ Partials      123        0     -123     

Flag	Coverage Δ
cypress	?
javascript	?
python	63.40% <ø> (-0.61%)	⬇️

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

Impacted Files	Coverage Δ
superset/db_engines/hive.py	0.00% <0.00%> (-85.72%)	⬇️
superset/sql_validators/postgres.py	50.00% <0.00%> (-50.00%)	⬇️
superset/db_engine_specs/hive.py	73.84% <0.00%> (-10.00%)	⬇️
superset/databases/commands/create.py	83.67% <0.00%> (-8.17%)	⬇️
superset/databases/commands/update.py	85.71% <0.00%> (-8.17%)	⬇️
superset/connectors/sqla/models.py	84.31% <0.00%> (-6.28%)	⬇️
superset/db_engine_specs/sqlite.py	90.62% <0.00%> (-6.25%)	⬇️
superset/databases/commands/test_connection.py	84.78% <0.00%> (-4.35%)	⬇️
superset/utils/celery.py	96.42% <0.00%> (-3.58%)	⬇️
superset/models/core.py	85.59% <0.00%> (-3.27%)	⬇️
... and 561 more

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