Add a CAPTCHA check during registration

.github/workflows/backend-tests.yml

@@ -25,7 +25,7 @@ jobs:
             ~/.cargo/registry
             ~/.cargo/git
             target
-          key: ${{ runner.os }}-cargo-${{ hashFiles('**/Cargo.lock') }}-1
+          key: ${{ runner.os }}-cargo-dummy-captcha-${{ hashFiles('**/Cargo.lock') }}-1
 
       - name: Cache ~/.cabal/store
         uses: actions/cache@v2
@@ -66,7 +66,9 @@ jobs:
 
       - name: Build backend canister
         run: |
-          cargo build --target wasm32-unknown-unknown --release
+          # we use the dummy_captcha feature which ensures the captcha string
+          # is always "a"
+          cargo build --features dummy_captcha --target wasm32-unknown-unknown --release
 
       - name: Run Tests
         shell: bash

.github/workflows/selenium.yml

@@ -68,6 +68,9 @@ jobs:
       - name: Deploy Internet Identity
         run: |
           export II_ENV=development
+          # we use the dummy_captcha feature which ensures the captcha string
+          # is always "a"
+          export USE_DUMMY_CAPTCHA=1
           dfx deploy --no-wallet --argument '(null)'
 
       - name: Deploy whoami canister