install dbt thingies in CI

.azure-pipelines.yml

@@ -34,6 +34,19 @@ steps:
     psql -h $POSTGRES_HOST -U $POSTGRES_USER -d postgres -c "CREATE DATABASE ci_${BUILD_SOURCEBRANCH#refs/heads/}"
   displayName: 'Create branch dedicated database'
 
+- script: |
+    python -m venv venv
+    source venv/bin/activate
+    pip install -r requirements.txt
+
+  displayName: 'Create python virtual environment'
+
+- script: |
+    source venv/bin/activate
+    dbt deps
+
+  displayName: 'Install dbt deps'
+
 - script: |
     cp ~/dbt-ci/.env .
     echo "POSTGRES_DATABASE=${BUILD_SOURCEBRANCH#refs/heads/}" >> .env