Update devcontainer file (#103)

.devcontainer/Dockerfile

@@ -3,7 +3,12 @@ FROM ghcr.io/home-assistant/devcontainer:addons
 RUN \
   apt-get update \
   && apt-get install -y --no-install-recommends \
-    python3-pip
+    python3-pip \
+    python3-venv
+
+ENV VIRTUAL_ENV=/opt/venv
+RUN python3 -m venv $VIRTUAL_ENV
+ENV PATH="$VIRTUAL_ENV/bin:$PATH"
 
 COPY script/requirements.txt /
 

.devcontainer/devcontainer.json

@@ -14,9 +14,12 @@
   "containerEnv": {
     "WORKSPACE_DIRECTORY": "${containerWorkspaceFolder}"
   },
+  "customizations": {
+    "vscode": {
       "extensions": [
         "timonwong.shellcheck",
-    "esbenp.prettier-vscode"
+        "esbenp.prettier-vscode",
+        "ms-python.python"
       ],
       "mounts": [
         "type=volume,target=/var/lib/docker"
@@ -34,3 +37,5 @@
         "files.trimTrailingWhitespace": true
       }
     }
+  }
+}