Merge pull request #154 from nickbabcock/ci

Specify timescale version to fix CI

ci/Dockerfile.timescale

@@ -1,3 +1,3 @@
-FROM timescale/timescaledb
+FROM timescale/timescaledb:latest-pg12
 COPY ci/setup-docker.sh /docker-entrypoint-initdb.d/.
 COPY assets/schema.sql /sql/schema.sql