chore(docker): ignore tmp + log files (#643)

Co-authored-by: Andi Pieper <apieper@mozilla.com>

Author: caugner

.dockerignore

@@ -10,5 +10,10 @@ target/
 !target/release/rumba
 **/.terraform/*
 
+# Exclude Temporary and Log Files.
+# See: https://wiki.mozilla.org/GitHub/Repository_Security/GitHub_Workflows_%26_Actions#Docker_Security_Best_Practices
+*.log
+*.tmp
+
 # Ignore generated credentials from google-github-actions/auth
 gha-creds-*.json