Bump certifi from 2022.12.7 to 2023.7.22 in /model_signing/install (#8)

Bumps [certifi](https://github.com/certifi/python-certifi) from 2022.12.7 to 2023.7.22.
- [Commits](certifi/python-certifi@2022.12.07...2023.07.22)

---
updated-dependencies:
- dependency-name: certifi
  dependency-type: direct:production
...

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

model_signing/install/requirements.txt

@@ -12,9 +12,9 @@ betterproto==2.0.0b5 \
     --hash=sha256:00a301c70a2db4d3cdd2b261522ae1d34972fb04b655a154d67daaaf4131102e \
     --hash=sha256:d3e6115c7d5136f1d5974e565b7560273f66b43065e74218e472321ee1258f4c
     # via sigstore-protobuf-specs
-certifi==2022.12.7 \
-    --hash=sha256:35824b4c3a97115964b408844d64aa14db1cc518f6562e8d7261699d1350a9e3 \
-    --hash=sha256:4ad3232f5e926d6718ec31cfc1fcadfde020920e278684144551c91769c7bc18
+certifi==2023.7.22 \
+    --hash=sha256:539cc1d13202e33ca466e88b2807e29f4c13049d6d87031a3c110744495cb082 \
+    --hash=sha256:92d6037539857d8206b8f6ae472e8b77db8058fec5937a1ef3f54304089edbb9
     # via requests
 cffi==1.15.1 \
     --hash=sha256:00a9ed42e88df81ffae7a8ab6d9356b371399b91dbdf0c3cb1e84c03a13aceb5 \