CI: don't build foundry from source

the upgrade script just uses docker now

.github/workflows/build.yml

@@ -8,9 +8,9 @@ on:
 jobs:
   # Run the full Tilt build and wait for it to converge
   tilt:
-    # in the future, we may want to run cheap lints, tests, and builds before firing up the expensive tilt test. 
+    # in the future, we may want to run cheap lints, tests, and builds before firing up the expensive tilt test.
     # But for now, we'll kick-off everything at once
-    # needs: [go-lint-and-tests, node, algorand, ethereum, terra, rust-lint-and-tests] 
+    # needs: [go-lint-and-tests, node, algorand, ethereum, terra, rust-lint-and-tests]
     runs-on: tilt-kube-public
 
     # Cancel previous builds on the same branch/ref. Full runs are expensive
@@ -75,20 +75,7 @@ jobs:
         with:
           node-version: "16"
       - run: cd clients/js && make install
-      - id: cache-foundry
-        uses: actions/cache@v3
-        with:
-          path: $HOME/.foundry
-          key: ${{ runner.os }}-foundry
-
-      - if: steps.cache-foundry.outputs.cache-hit != 'true'
-        run: curl -L https://foundry.paradigm.xyz | bash
-
-      - name: Install foundry
-        if: steps.cache-foundry.outputs.cache-hit != 'true'
-        run: $HOME/.foundry/bin/foundryup -C 4367ce1c3d2c10b71350b40258766d53a94c717f
-
-      - run: cd ethereum && PATH=$PATH:$HOME/.foundry/bin/ make test-upgrade
+      - run: cd ethereum && make test-upgrade
 
   terra:
     runs-on: ubuntu-20.04