fix: 'Run in SQL Lab' redirect bug

[mistercrunch]

SUMMARY

Fix a bug related to a POST + redirect issue, adding a trailing backslash fixes things

BEFORE/AFTER SCREENSHOTS OR ANIMATED GIF

TEST PLAN

Manual

[codecov]

Codecov Report

Merging #13657 (2898678) into master (21cc495) will decrease coverage by 4.26%.
The diff coverage is 0.00%.

❗ Current head 2898678 differs from pull request most recent head 1eab3d0. Consider uploading reports for the commit 1eab3d0 to get more accurate results

@@            Coverage Diff             @@
##           master   #13657      +/-   ##
==========================================
- Coverage   77.41%   73.14%   -4.27%     
==========================================
  Files         918      608     -310     
  Lines       46673    21653   -25020     
  Branches     5720     5720              
==========================================
- Hits        36131    15838   -20293     
+ Misses      10406     5679    -4727     
  Partials      136      136              

Flag	Coverage Δ
cypress	56.58% <0.00%> (-0.01%)	⬇️
hive	?
javascript	63.17% <0.00%> (ø)
mysql	?
postgres	?
presto	?
python	?
sqlite	?

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Impacted Files	Coverage Δ
superset-frontend/src/chart/chartAction.js	78.00% <0.00%> (ø)
...set-frontend/src/dashboard/util/getDropPosition.js	90.90% <0.00%> (-1.52%)	⬇️
superset/queries/dao.py
superset/charts/commands/create.py
superset/annotation_layers/commands/bulk_delete.py
superset/models/cache.py
superset/reports/api.py
superset/security/__init__.py
superset/models/__init__.py
superset/queries/saved_queries/schemas.py
... and 302 more

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