Update devcontainer.json (rust-lang#494)

Author: tgymnich

.devcontainer/devcontainer.json

@@ -1,8 +1,8 @@
 // available ubuntu versions: [18, 20]
-// available llvm versions: [7, 8, 9, 10, 11, 12]
+// available llvm versions: [7, 8, 9, 10, 11, 12, 13]
 {
     "name": "Enzyme",
-    "image": "ghcr.io/tgymnich/enzyme-dev-docker/ubuntu-20-llvm-12:latest",
+    "image": "ghcr.io/enzymead/enzyme-dev-docker/ubuntu-20-llvm-12:latest",
     "mounts": [
         "source=enzyme-bashhistory,target=/commandhistory,type=volume",
         "source=enzyme-extensions,target=/root/.vscode-server/extensions,type=volume",