fix(devcontainer): ensure pip is installed in the devcontainer

this is being done because Red-DiscordBot requires pip to be installed to function, but does not declare it as a dependency. this is only a problem when uv is being used to install dependencies in an environment where pip is not present. so, we ensure pip is present!

.devcontainer/Dockerfile

@@ -31,4 +31,5 @@ COPY --from=uv --chown=vscode: /uv /uvx /bin/
 COPY --from=python --chown=vscode: /usr/local /usr/local
 
 RUN ln -s /usr/local/bin/python3.11 /usr/local/bin/python; \
-    python --version
+    python --version; \
+    python -m ensurepip