Use official uv cache method

Author: nateinaction

.github/workflows/ci.yaml

@@ -17,6 +17,8 @@ jobs:
 
   build:
     runs-on: ubuntu-latest
+    env:
+      UV_CACHE_DIR: /tmp/.uv-cache
 
     steps:
     - name: Checkout repository
@@ -26,7 +28,6 @@ jobs:
         fetch-depth: 0
 
     - name: Cache bin
-      id: cache-bin
       uses: actions/cache@v4
       with:
         path: |
@@ -59,18 +60,16 @@ jobs:
       run: |
         make submodules
 
-    - name: Cache python venv
-      id: cache-python
+    - name: Restore uv cache
       uses: actions/cache@v4
       with:
-        path: fprime-venv
-        key: python-venv-${{ runner.os }}-${{ hashFiles('uv.lock') }}-v3
-        restore-keys: |
-          python-venv-${{ runner.os }}-
-          python-venv-
+          path: /tmp/.uv-cache
+          key: uv-${{ runner.os }}-${{ hashFiles('uv.lock') }}
+          restore-keys: |
+            uv-${{ runner.os }}-${{ hashFiles('uv.lock') }}
+            uv-${{ runner.os }}
 
     - name: Setup python venv
-      if: steps.cache-python.outputs.cache-hit != 'true'
       run: |
         make fprime-venv
 
@@ -107,3 +106,6 @@ jobs:
           build-artifacts/zephyr.uf2
           build-artifacts/zephyr/fprime-zephyr-deployment/dict/ReferenceDeploymentTopologyDictionary.json
         retention-days: 30
+
+    - name: Minimize uv cache
+      run: uv cache prune --ci