per-key cache

Change-Id: I237362487aecd4e7e4a1ccbc281c67d2c31c65d9
Signed-off-by: Tom Proctor <tomhjp@users.noreply.github.com>

.github/workflows/win.yml

@@ -24,7 +24,7 @@ jobs:
         path: src
     - uses: actions/cache@0057852bfaa89a56745cba8c7296529d2fc39830 # v4.3.0
       with:
-        key: go-win-dev-drive-${{ hashFiles('src/go.mod', 'src/go.sum') }}"
+        key: ${{ matrix.key }}-dev-drive-${{ hashFiles('src/go.mod', 'src/go.sum') }}"
         path: C:\\dev_disk.vhdx
     - uses: samypr100/setup-dev-drive@30f0f98ae5636b2b6501e181dfb3631b9974818d # v4.0.0
       with: