Pin to 1.91.1 toolchain for CI

Author: emmatyping

.github/workflows/build.yml

@@ -383,7 +383,7 @@ jobs:
       - uses: actions/checkout@v4
         with:
           persist-credentials: false
-      - uses: dtolnay/rust-toolchain@master
+      - uses: dtolnay/rust-toolchain@1.91.1
         with:
           targets: ${{ matrix.arch }}-linux-android
       - name: Build and test
@@ -399,7 +399,7 @@ jobs:
       - uses: actions/checkout@v4
         with:
           persist-credentials: false
-      - uses: dtolnay/rust-toolchain@master
+      - uses: dtolnay/rust-toolchain@1.91.1
         with:
           targets: aarch64-apple-ios-sim
       # GitHub recommends explicitly selecting the desired Xcode version:

.github/workflows/reusable-wasi.yml

@@ -48,7 +48,7 @@ jobs:
       uses: actions/setup-python@v5
       with:
         python-version: '3.x'
-    - uses: dtolnay/rust-toolchain@master
+    - uses: dtolnay/rust-toolchain@1.91.1
       with:
         targets: wasm32-wasip1
     - name: "Runner image version"