Update devcontainer.json

Author: benpaddlejones

.devcontainer/devcontainer.json

@@ -40,7 +40,7 @@
         "esbenp.prettier-vscode",
         "oderwat.indent-rainbow",
         "ritwickdey.LiveServer",
-        "tomoki1207.pdf",
+        "mathematic.vscode-pdf",
         "GitHub.codespaces",
         "ms-python.debugpy",
         "ms-python.vscode-pylance",