build(deps): bump sigstore/sigstore-conformance in the actions group (sigstore#1311)

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

.github/workflows/conformance.yml

@@ -24,7 +24,7 @@ jobs:
       - name: install sigstore-python
         run: python -m pip install .
 
-      - uses: sigstore/sigstore-conformance@d658ea74a060aeabae78f8a379167f219dc38c38 # v0.0.16
+      - uses: sigstore/sigstore-conformance@640e7dfb715518eeeb492910c6d244cedcc6cfea # v0.0.17
         with:
           entrypoint: ${{ github.workspace }}/test/integration/sigstore-python-conformance
           xfail: "test_verify_with_trust_root test_verify_dsse_bundle_with_trust_root" # see issue 821