update bw to 4.3, add .provides() to metadata reactors

Jenkinsfile

@@ -34,6 +34,18 @@ pipeline {
                         """
                     }
                 }
+                stage('reactor.provides') {
+                    when {
+                        branch 'main'
+                    }
+                    steps {
+                        sh """
+                            . venv/bin/activate
+                            export BW_VAULT_DUMMY_MODE=1
+                            bw test -p
+                        """
+                    }
+                }
                 stage('determinism') {
                     steps {
                         sh """