Update Rust in CI to v1.87.0 as well as dtolnay/rust-toolchain GitHub Action pinned commit hash (#18596)

.github/workflows/twisted_trunk.yml

@@ -20,6 +20,9 @@ concurrency:
   group: ${{ github.workflow }}-${{ github.ref }}
   cancel-in-progress: true
 
+env:
+  RUST_VERSION: 1.87.0
+
 jobs:
   check_repo:
     # Prevent this workflow from running on any fork of Synapse other than element-hq/synapse, as it is
@@ -43,7 +46,9 @@ jobs:
       - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
 
       - name: Install Rust
-        uses: dtolnay/rust-toolchain@fcf085fcb4b4b8f63f96906cd713eb52181b5ea4 # stable (rust 1.85.1)
+        uses: dtolnay/rust-toolchain@b3b07ba8b418998c39fb20f53e8b695cdcc8de1b # master
+        with:
+          toolchain: ${{ env.RUST_VERSION }}
       - uses: Swatinem/rust-cache@98c8021b550208e191a6a3145459bfc9fb29c4c0 # v2.8.0
 
       - uses: matrix-org/setup-python-poetry@5bbf6603c5c930615ec8a29f1b5d7d258d905aa4 # v2.0.0
@@ -69,7 +74,9 @@ jobs:
       - run: sudo apt-get -qq install xmlsec1
 
       - name: Install Rust
-        uses: dtolnay/rust-toolchain@fcf085fcb4b4b8f63f96906cd713eb52181b5ea4 # stable (rust 1.85.1)
+        uses: dtolnay/rust-toolchain@b3b07ba8b418998c39fb20f53e8b695cdcc8de1b # master
+        with:
+          toolchain: ${{ env.RUST_VERSION }}
       - uses: Swatinem/rust-cache@98c8021b550208e191a6a3145459bfc9fb29c4c0 # v2.8.0
 
       - uses: matrix-org/setup-python-poetry@5bbf6603c5c930615ec8a29f1b5d7d258d905aa4 # v2.0.0
@@ -113,7 +120,9 @@ jobs:
       - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
 
       - name: Install Rust
-        uses: dtolnay/rust-toolchain@fcf085fcb4b4b8f63f96906cd713eb52181b5ea4 # stable (rust 1.85.1)
+        uses: dtolnay/rust-toolchain@b3b07ba8b418998c39fb20f53e8b695cdcc8de1b # master
+        with:
+          toolchain: ${{ env.RUST_VERSION }}
       - uses: Swatinem/rust-cache@98c8021b550208e191a6a3145459bfc9fb29c4c0 # v2.8.0
 
       - name: Patch dependencies