Install requirements.txt by default during dev env spin up (#1099)

I bumped the astronomer image to 11.6 since it uses the newest airflow,
incorporating [tatiana's change in airflow
version](apache/airflow#39670) for datasets and
I am installing requirements.txt by default in the image, since if the
user wants to add some custom package, he needs to change not only the
requirements.txt file but also the Dockerfile. With this only adding
dependencies to requirements.txt will already install them in the image
for dev development.

dev/Dockerfile

@@ -1,4 +1,4 @@
-FROM quay.io/astronomer/astro-runtime:11.3.0-base
+FROM quay.io/astronomer/astro-runtime:11.6.0-base
 
 USER root
 
@@ -15,9 +15,11 @@ RUN pip install -U uv
 COPY ./pyproject.toml  ${AIRFLOW_HOME}/astronomer_cosmos/
 COPY ./README.rst  ${AIRFLOW_HOME}/astronomer_cosmos/
 COPY ./cosmos/  ${AIRFLOW_HOME}/astronomer_cosmos/cosmos/
-
+COPY ./dev/requirements.txt ${AIRFLOW_HOME}/requirements.txt
 # install the package in editable mode
-RUN uv pip install --system -e "${AIRFLOW_HOME}/astronomer_cosmos"[dbt-postgres,dbt-databricks]
+RUN uv pip install --system -e "${AIRFLOW_HOME}/astronomer_cosmos"[dbt-postgres,dbt-databricks] && \
+    uv pip install --system -r ${AIRFLOW_HOME}/requirements.txt
+
 
 # make sure astro user owns the package
 RUN chown -R astro:astro ${AIRFLOW_HOME}/astronomer_cosmos