chore: fix bazel extractor dockerfile (#5334)

diff --git a/kythe/extractors/bazel/Dockerfile b/kythe/extractors/bazel/Dockerfile
index 335db58..49f5e9c 100644
--- a/kythe/extractors/bazel/Dockerfile
+++ b/kythe/extractors/bazel/Dockerfile
@@ -15,9 +15,9 @@
 FROM debian:sid
 
 # Install C++ compilers and other deps
-# note that openjdk-8-jdk is a dependency of the java extractor
+# note that openjdk-11-jdk-headless is a dependency of the java extractor
 RUN apt-get update && \
-    apt-get install -y git clang-11 build-essential zip python openjdk-8-jdk && \
+    apt-get install -y git clang-11 build-essential zip python3 openjdk-11-jdk-headless && \
     apt-get clean
 
 # Create clang symlinks