Fix Jenkins oldev build

Jenkins rebuilds the oldev image when pip dependencies change, so
it needs to be able to set the nexus URL for package repos in the
build.

docker/Dockerfile.oldev

@@ -1,4 +1,11 @@
 FROM openlibrary/olbase:latest
+
+# Allow for nexus overrides (used in testing/staging builds)
+ARG NPM_CONFIG_REGISTRY
+ARG PIP_INDEX_URL
+ARG PIP_TRUSTED_HOST
+ARG HTTPS_PROXY
+
 WORKDIR /openlibrary
 
 COPY --chown=openlibrary:openlibrary requirements*.txt ./