fix: Update Dockerfile to fix cloud sdk repository change

fixes GoogleCloudPlatform#88

cloudrun-malware-scanner/Dockerfile

@@ -39,6 +39,8 @@ ENV PATH "$PATH:/opt/google-cloud-sdk/bin/"
 RUN export DEBIAN_FRONTEND=noninteractive && \
     apt-get update -qqy && \
     apt-get install -qqy --no-install-recommends  \
+        apt-transport-https \
+        ca-certificates \
         curl \
         python3-pip \
         pipx \
@@ -57,12 +59,11 @@ RUN export DEBIAN_FRONTEND=noninteractive && \
         clamav-base \
         clamav-daemon \
         clamav-freshclam && \
-    CLOUD_SDK_REPO="cloud-sdk-$(lsb_release -c -s)" && \
     echo -n "Adding Cloud SDK apt repository: " && \
-    echo "deb https://packages.cloud.google.com/apt $CLOUD_SDK_REPO main" \
-        | tee /etc/apt/sources.list.d/google-cloud-sdk.list && \
-    curl -s https://packages.cloud.google.com/apt/doc/apt-key.gpg \
-        | gpg --dearmor -o /etc/apt/trusted.gpg.d/packages-cloud-google-apt.gpg && \
+    echo "deb [signed-by=/usr/share/keyrings/cloud.google.gpg] https://packages.cloud.google.com/apt cloud-sdk main" \
+        | tee -a /etc/apt/sources.list.d/google-cloud-sdk.list && \
+    curl https://packages.cloud.google.com/apt/doc/apt-key.gpg \
+        | gpg --dearmor -o /usr/share/keyrings/cloud.google.gpg && \
     apt-get update -qqy && \
     apt-get install -qqy --no-install-recommends google-cloud-sdk && \
     gcloud config set core/disable_usage_reporting true && \