Pin setup-uv docs to v8 (#829)

Update all README and docs examples to use the pinned v8 release SHA for
astral-sh/setup-uv, with a comment showing the release version for
clarity and best practices.

docs/environment-and-tools.md

@@ -9,7 +9,7 @@ This allows directly using it in later steps:
 
 ```yaml
 - name: Install the latest version of uv and activate the environment
-  uses: astral-sh/setup-uv@v7
+  uses: astral-sh/setup-uv@cec208311dfd045dd5311c1add060b2062131d57 # v8.0.0
   with:
     activate-environment: true
 - run: uv pip install pip
@@ -20,7 +20,7 @@ By default, the venv is created at `.venv` inside the `working-directory`.
 You can customize the venv location with `venv-path`, for example to place it in the runner temp directory:
 
 ```yaml
-- uses: astral-sh/setup-uv@v7
+- uses: astral-sh/setup-uv@cec208311dfd045dd5311c1add060b2062131d57 # v8.0.0
   with:
     activate-environment: true
     venv-path: ${{ runner.temp }}/custom-venv
@@ -51,7 +51,7 @@ are not sufficient, you can provide a custom GitHub token with the necessary per
 
 ```yaml
 - name: Install the latest version of uv with a custom GitHub token
-  uses: astral-sh/setup-uv@v7
+  uses: astral-sh/setup-uv@cec208311dfd045dd5311c1add060b2062131d57 # v8.0.0
   with:
     github-token: ${{ secrets.CUSTOM_GITHUB_TOKEN }}
 ```
@@ -69,7 +69,7 @@ input:
 
 ```yaml
 - name: Install the latest version of uv with a custom tool dir
-  uses: astral-sh/setup-uv@v7
+  uses: astral-sh/setup-uv@cec208311dfd045dd5311c1add060b2062131d57 # v8.0.0
   with:
     tool-dir: "/path/to/tool/dir"
 ```
@@ -88,7 +88,7 @@ If you want to change this behaviour (especially on self-hosted runners) you can
 
 ```yaml
 - name: Install the latest version of uv with a custom tool bin dir
-  uses: astral-sh/setup-uv@v7
+  uses: astral-sh/setup-uv@cec208311dfd045dd5311c1add060b2062131d57 # v8.0.0
   with:
     tool-bin-dir: "/path/to/tool-bin/dir"
 ```
@@ -105,7 +105,7 @@ This action supports expanding the `~` character to the user's home directory fo
 
 ```yaml
 - name: Expand the tilde character
-  uses: astral-sh/setup-uv@v7
+  uses: astral-sh/setup-uv@cec208311dfd045dd5311c1add060b2062131d57 # v8.0.0
   with:
     cache-local-path: "~/path/to/cache"
     tool-dir: "~/path/to/tool/dir"
@@ -122,7 +122,7 @@ If you want to ignore this, set the `ignore-empty-workdir` input to `true`.
 
 ```yaml
 - name: Ignore empty workdir
-  uses: astral-sh/setup-uv@v7
+  uses: astral-sh/setup-uv@cec208311dfd045dd5311c1add060b2062131d57 # v8.0.0
   with:
     ignore-empty-workdir: true
 ```
@@ -145,7 +145,7 @@ This action sets several environment variables that influence uv's behavior and
 
 ```yaml
 - name: Example using environment variables
-  uses: astral-sh/setup-uv@v7
+  uses: astral-sh/setup-uv@cec208311dfd045dd5311c1add060b2062131d57 # v8.0.0
   with:
     python-version: "3.12"
     tool-dir: "/custom/tool/dir"