Unit test CI step (#136)

## Type of change

<!--Delete points that do not apply-->

- Improvement (refactoring, restructuring repository, cleaning tech
debt, ...)

## Changes

Added a CI unit test step

## Notes

- Note 1

## Related Issues

<!--Delete everything after the "#" symbol and replace it with a number.
No spaces between hash and number-->

Closes #135

.github/workflows/ci.yml

@@ -73,6 +73,31 @@ jobs:
           run: |
             cargo test --manifest-path tests/Cargo.toml
 
+  forc-unit-tests:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v2
+
+      - name: Install Rust toolchain
+        uses: actions-rs/toolchain@v1
+        with:
+          profile: minimal
+          toolchain: ${{ env.RUST_VERSION }}
+          override: true
+
+      - name: Init cache
+        uses: Swatinem/rust-cache@v1
+
+      - name: Install Fuel toolchain
+        uses: FuelLabs/action-fuel-toolchain@v0.6.0
+        with:
+          name: my-toolchain
+          components: forc@${{ env.FORC_VERSION }}, fuel-core@${{ env.CORE_VERSION }}
+
+      - name: Run Unit Tests
+        run: forc build --path libs && forc test --path libs
+
   build-standards:
       runs-on: ubuntu-latest