fix: ensure we can execute run commands when exec is executed as part of an entrypoint

Closes #8052

tests/apps/python/exec-entrypoint.sh

@@ -0,0 +1,4 @@
+#!/bin/bash
+set -o pipefail
+
+exec "$@"

tests/apps/python/exec.Dockerfile

@@ -0,0 +1,11 @@
+FROM python:3.12.6-bookworm
+
+EXPOSE 3001/udp
+EXPOSE  3000/tcp
+EXPOSE 3003
+
+COPY . /app
+
+WORKDIR /app
+
+ENTRYPOINT ["/app/exec-entrypoint.sh"]

tests/apps/python/exec.Procfile

@@ -0,0 +1 @@
+task: echo 'hi dokku'