update rust in runas.yml

Author: usamoi

.github/workflows/runas.yml

@@ -9,6 +9,7 @@ on:
 env:
   CARGO_TERM_COLOR: always
   RUST_BACKTRACE: 1
+  TOOL_DIR: ./tools
 
 jobs:
   ubuntu:
@@ -20,6 +21,10 @@ jobs:
         with:
           prefix-key: "v1-cargo-pgrx-test--runas"
 
+      - name: Install Rust
+        run: |
+          "$TOOL_DIR"/rustup.sh
+
       - name: Install Postgres deps
         run: |
           sudo apt-get update -y -qq --fix-missing