Bump sigstore from 2.1.0 to 2.1.2 in /.github/requirements

Bumps [sigstore](https://github.com/sigstore/sigstore-python) from 2.1.0 to 2.1.2.
- [Release notes](https://github.com/sigstore/sigstore-python/releases)
- [Changelog](https://github.com/sigstore/sigstore-python/blob/main/CHANGELOG.md)
- [Commits](sigstore/sigstore-python@v2.1.0...v2.1.2)

---
updated-dependencies:
- dependency-name: sigstore
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <[email protected]>

.github/requirements/publish-requirements.txt

@@ -246,6 +246,10 @@ importlib-metadata==7.0.1 \
     # via
     #   keyring
     #   twine
+importlib-resources==5.13.0 \
+    --hash=sha256:82d5c6cca930697dbbd86c93333bb2c2e72861d4789a11c2662b933e5ad2b528 \
+    --hash=sha256:9f7bd0c97b79972a6cce36a366356d16d5e13b09679c11a58f1014bfdf8e64b2
+    # via sigstore
 jaraco-classes==3.3.0 \
     --hash=sha256:10afa92b6743f25c0cf5f37c6bb6e18e2c5bb84a16527ccfc0040ea377e7aaeb \
     --hash=sha256:c063dd08e89217cee02c8d5e5ec560f2c8ce6cdc2fcdc2e68f7b2e5547ed3621
@@ -560,9 +564,9 @@ securesystemslib==0.31.0 \
     # via
     #   sigstore
     #   tuf
-sigstore==2.1.0 \
-    --hash=sha256:68761c3078aca9bb97af8459602959ff47ce648bf722a8c2c868e45b46aad7e1 \
-    --hash=sha256:7c64b4c6eccee0ec1b54d524d7be57dabc1f1f3651dd723cf195aa6b1f94b4f7
+sigstore==2.1.2 \
+    --hash=sha256:94139c1efa0784135516d11b79c8b06d4ea61245624e69cda44494e87560b07c \
+    --hash=sha256:fd9069b50b5789c6e229641e948a9b47c07525e8924f5e4d20d7dc1a8db6d6e2
     # via -r publish-requirements.in
 sigstore-protobuf-specs==0.2.2 \
     --hash=sha256:62c7beabc6910fb570dc4c600e33e81f2d2d683f785202ee109ca394bd829e94 \