Bump actions/cache from 4 to 5

Bumps [actions/cache](https://github.com/actions/cache) from 4 to 5.
- [Release notes](https://github.com/actions/cache/releases)
- [Changelog](https://github.com/actions/cache/blob/main/RELEASES.md)
- [Commits](actions/cache@v4...v5)

---
updated-dependencies:
- dependency-name: actions/cache
  dependency-version: '5'
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

.github/workflows/ci.yml

@@ -25,7 +25,7 @@ jobs:
 
       - name: Load cached Poetry installation
         id: cached-poetry
-        uses: actions/cache@v4
+        uses: actions/cache@v5
         with:
           path: ~/.local
           key: poetry-${{ env.POETRY_VERSION }}-${{ runner.os }}
@@ -40,7 +40,7 @@ jobs:
 
       - name: Load cached venv
         id: cached-venv
-        uses: actions/cache@v4
+        uses: actions/cache@v5
         with:
           path: .venv
           key: venv-lint-${{ runner.os }}-py3.14-${{ hashFiles('poetry.lock') }}
@@ -71,7 +71,7 @@ jobs:
 
       - name: Load cached Poetry installation
         id: cached-poetry
-        uses: actions/cache@v4
+        uses: actions/cache@v5
         with:
           path: ~/.local
           key: poetry-${{ env.POETRY_VERSION }}-${{ runner.os }}
@@ -86,7 +86,7 @@ jobs:
 
       - name: Load cached venv
         id: cached-venv
-        uses: actions/cache@v4
+        uses: actions/cache@v5
         with:
           path: .venv
           key: venv-test-${{ runner.os }}-py3.14-${{ hashFiles('poetry.lock') }}
@@ -132,7 +132,7 @@ jobs:
 
       - name: Load cached Poetry installation
         id: cached-poetry
-        uses: actions/cache@v4
+        uses: actions/cache@v5
         with:
           path: ~/.local
           key: poetry-${{ env.POETRY_VERSION }}-${{ runner.os }}
@@ -147,7 +147,7 @@ jobs:
 
       - name: Load cached venv
         id: cached-venv
-        uses: actions/cache@v4
+        uses: actions/cache@v5
         with:
           path: .venv
           key: venv-security-${{ runner.os }}-py3.14-${{ hashFiles('poetry.lock') }}