BLD: Upload sdist artifact from CI (pandas-dev#46277)

* BLD: Upload sdist artifact from CI

Now it is possible to inspect the sdist that is built, to
see what was included and
for debugging.

Inspired by needing to see what was acutally included in the sdist at
pandas-dev#46271

* BLD: fix artifact name

Got this error before:
Error: Artifact name is not valid:
refs/pull/46277/merge-3.8-sdist.gz.
Contains the following character:  Forward slash /

This is more precise anyways.

* BLD: Drop SHA from sdist artifact name

Per
pandas-dev#46277 (comment)

Author: NickCrews

Diff for: .github/workflows/sdist.yml

@@ -52,6 +52,12 @@ jobs:
         pip list
         python setup.py sdist --formats=gztar
 
+    - name: Upload sdist artifact
+      uses: actions/upload-artifact@v3
+      with:
+        name: ${{matrix.python-version}}-sdist.gz
+        path: dist/*.gz
+
     - uses: conda-incubator/setup-miniconda@v2
       with:
         activate-environment: pandas-sdist