chore: update Dockerfile.deps.* to use python3 (#8792)

Author: aaron-prindle

deploy/skaffold/Dockerfile.deps

@@ -119,7 +119,7 @@ FROM ubuntu:20.04 as runtime_deps
 
 RUN apt-get update && \
     apt-get install --no-install-recommends --no-install-suggests -y \
-    git python unzip && \
+    git python3 unzip && \
     rm -rf /var/lib/apt/lists/*
 
 COPY --from=docker:19.03.13 /usr/local/bin/docker /usr/local/bin/

deploy/skaffold/Dockerfile.deps.lts

@@ -72,7 +72,7 @@ FROM ubuntu:20.04 as runtime_deps
 
 RUN apt-get update && \
     apt-get install --no-install-recommends --no-install-suggests -y \
-    git python unzip && \
+    git python3 unzip && \
     rm -rf /var/lib/apt/lists/*
 
 COPY --from=download-kubectl kubectl /usr/local/bin/