build(Dockerfile): adding a ENV on the virtual environment might do it

server-scripts/desec-ip-sync/Dockerfile

@@ -10,7 +10,7 @@ RUN apt update && apt install python3.11-venv -y
 
 RUN bash run.bash
 
-RUN source venv/bin/activate
+ENV PATH="$PWD/venv/bin:$PATH"
 
 CMD ["python3", "main.py"]
 

server-scripts/desec-ip-sync/requirements.txt

@@ -0,0 +1,2 @@
+python-dotenv
+requests

server-scripts/desec-ip-sync/run.bash

@@ -9,7 +9,7 @@ fi
 if [ ! -d venv ]; then
 	python3 -m venv venv
 	source venv/bin/activate
-	pip install -U python-dotenv requests
+	pip install -U -r requirements.txt
 	pip install -U pip # Update pip to the latest version
 else
 	source venv/bin/activate