sdk_lib: Silence some docker warnings

Author: krnowak

sdk_lib/Dockerfile.lean-arch

@@ -1,4 +1,4 @@
-ARG VERSION
+ARG VERSION=9999.99.99-version-missing
 
 FROM flatcar-sdk-build:${VERSION} as meta
 ARG RMARCH
@@ -26,4 +26,4 @@ RUN chown -R sdk:sdk /mnt/host/source
 #  but it's useful for standalone container use.
 RUN mkdir -p /mnt/host/source/src/scripts
 COPY --chown=sdk:sdk sdk_lib/sdk_init_selfcontained.sh /mnt/host/source/src/
-ENTRYPOINT /home/sdk/sdk_entry.sh
+ENTRYPOINT ["/home/sdk/sdk_entry.sh"]

sdk_lib/Dockerfile.sdk-build

@@ -1,4 +1,4 @@
-ARG VERSION
+ARG VERSION=9999.99.99-version-missing
 FROM flatcar-sdk-import:${VERSION}
 
 ARG BINHOST

sdk_lib/Dockerfile.sdk-import

@@ -1,4 +1,4 @@
-ARG VERSION
+ARG VERSION=9999.99.99-version-missing
 FROM flatcar-sdk-tarball:${VERSION}
 
 # Make build scripts believe we're in the SDK chroot (which technically, we are)
@@ -55,4 +55,4 @@ RUN chmod 755 /home/sdk/sdk_entry.sh
 #  it's likely that scripts and SDK tarball are out of sync
 RUN /home/sdk/sdk_entry.sh ./update_chroot --toolchain_boards="amd64-usr arm64-usr"
 
-ENTRYPOINT /home/sdk/sdk_entry.sh
+ENTRYPOINT ["/home/sdk/sdk_entry.sh"]