CI workflow: installs Foundry through official GH action.

This caches a particular release across action runners, lowering the
chance of running into a 403 unauthorized access in GitHub.

.github/workflows/test.yaml

@@ -23,20 +23,22 @@ jobs:
           cache-dependency-path: |
             ethereum/package-lock.json
             ethereum/wormhole/ethereum/package-lock.json
+      - name: Install Foundry
+        uses: foundry-rs/foundry-toolchain@v1
       - name: Run forge unit tests
         run: |
           cd ethereum
-          ../scripts/install-foundry
-          PATH=$PATH:$HOME/.foundry/bin/ make unit-test
+          make unit-test
   format:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v3
+      - name: Install Foundry
+        uses: foundry-rs/foundry-toolchain@v1
       - name: Check that contracts are formatted
         run: |
           cd ethereum
-          ../scripts/install-foundry
-          PATH=$PATH:$HOME/.foundry/bin/ forge fmt --check
+          forge fmt --check
   typecheck:
     runs-on: ubuntu-latest
     steps:
@@ -59,11 +61,12 @@ jobs:
             trustless-generic-relayer/ethereum/wormhole/ethereum/package-lock.json
             trustless-generic-relayer/relayer_engine/package-lock.json
             trustless-generic-relayer/sdk/package-lock.json
+      - name: Install Foundry
+        uses: foundry-rs/foundry-toolchain@v1
       - name: Generate contract typechain typings
         run: |
           cd trustless-generic-relayer/ethereum
-          ../scripts/install-foundry
-          PATH=$PATH:$HOME/.foundry/bin/ make build
+          make build
       - run: cd trustless-generic-relayer/sdk && npm ci
       - name: Typecheck ethereum/ts-scripts
         run: |
@@ -98,11 +101,12 @@ jobs:
             trustless-generic-relayer/ethereum/wormhole/ethereum/package-lock.json
             trustless-generic-relayer/relayer_engine/package-lock.json
             trustless-generic-relayer/sdk/package-lock.json
+      - name: Install Foundry
+        uses: foundry-rs/foundry-toolchain@v1
       - name: Generate contract typechain typings
         run: |
           cd trustless-generic-relayer/ethereum
-          ../scripts/install-foundry
-          PATH=$PATH:$HOME/.foundry/bin/ make build
+          make build
       - name: Typecheck relayer engine plugin
         run: |
           cd trustless-generic-relayer/relayer_engine