Update sigstore/cosign-installer action to v2.8.1 (#930)

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This PR contains the following updates:

| Package | Type | Update | Change |
|---|---|---|---|
|
[sigstore/cosign-installer](https://togithub.com/sigstore/cosign-installer)
| action | patch | `v2.8.0` -> `v2.8.1` |

---

### Release Notes

<details>
<summary>sigstore/cosign-installer</summary>

###
[`v2.8.1`](https://togithub.com/sigstore/cosign-installer/releases/tag/v2.8.1)

[Compare
Source](https://togithub.com/sigstore/cosign-installer/compare/v2.8.0...v2.8.1)

##### What's Changed

- bump cosign install to use release v1.13.1 by
[@&#8203;cpanato](https://togithub.com/cpanato) in
[sigstore/cosign-installer#98

**Full Changelog**:
sigstore/cosign-installer@v2...v2.8.1

</details>

---

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.github/workflows/build-rust-injector.yml

@@ -16,7 +16,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: "Dependency: Install cosign"
-        uses: sigstore/cosign-installer@v2.8.0
+        uses: sigstore/cosign-installer@v2.8.1
 
       - name: "Dependency: Setup rust toolchain"
         run: |

.github/workflows/release.yml

@@ -15,7 +15,7 @@ jobs:
           go-version: 1.19.x
 
       - name: "Dependency: Install cosign"
-        uses: sigstore/cosign-installer@v2.8.0
+        uses: sigstore/cosign-installer@v2.8.1
 
       - name: "Dependency: Install Syft"
         uses: anchore/sbom-action/download-syft@v0.12.0