try

circleci/images/exttester/Dockerfile

@@ -152,14 +152,23 @@ RUN <<'EOF'
 # install postgres ecosystem for pg version: $PG_VERSION
 set -eux
 
+DEBIAN_FRONTEND=noninteractive apt purge -y \
+    libpq5 \
+
+# debug
+ls -la /usr/lib/x86_64-linux-gnu/libpq.so*
+
+# remove the libpq.so* files if any
+rm /usr/lib/x86_64-linux-gnu/libpq.so* | true
+
+# debug
+ls -la /usr/lib/x86_64-linux-gnu/libpq.so*
+
 # install key and repositories
 curl -sf https://www.postgresql.org/media/keys/ACCC4CF8.asc | APT_KEY_DONT_WARN_ON_DANGEROUS_USAGE=1 apt-key add -
 echo "deb https://apt.postgresql.org/pub/repos/apt bullseye-pgdg main" >> /etc/apt/sources.list.d/postgresql.list
 echo "deb https://apt-archive.postgresql.org/pub/repos/apt bullseye-pgdg-archive main" >> /etc/apt/sources.list.d/postgresql.list
 
-DEBIAN_FRONTEND=noninteractive apt purge -y \
-    libpq5 \
-
 apt-get update
 
 # infer the pgdgversion of postgres based on the $PG_VERSION