Move away from deprecated Magic Nix Cache workflow step

Signed-off-by: Martin Baillie <[email protected]>

Author: martinbaillie

.github/workflows/test.yml

@@ -6,7 +6,7 @@ jobs:
     steps:
     - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
     - uses: DeterminateSystems/nix-installer-action@21a544727d0c62386e78b4befe52d19ad12692e3 # v17
-    - uses: DeterminateSystems/magic-nix-cache-action@def9f5a5c6a6b8751c0534e8813a5d0ad2635660 # v11
+    - uses: DeterminateSystems/flakehub-cache-action@134cf641155463d87d343c6cb2b7970089967b99 # v2
     - run: nix develop --command bash -c "lint && integration"
     - uses: codecov/codecov-action@1e68e06f1dbfde0e4cefc87efeba9e4643565303 # v5.1.2
       with: