Image build pipeline (#2613)

Signed-off-by: Raghav Kaul <raghavkaul@google.com>

attestor/cloudbuild.yaml

@@ -0,0 +1,24 @@
+# Copyright 2023 OpenSSF Scorecard Authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+steps:
+- id: 'Get Git history'
+  name: 'gcr.io/cloud-builders/git'
+  args: ['fetch', '--unshallow', '--tags', 'origin', '$COMMIT_SHA']
+- name: 'gcr.io/cloud-builders/docker'
+  args: ['build', '.',
+    '-t', 'gcr.io/openssf/scorecard-attestor:latest',
+    '-t', 'gcr.io/openssf/scorecard-attestor:$COMMIT_SHA',
+    '-f', 'attestor/Dockerfile']
+images: ['gcr.io/openssf/scorecard-attestor']