fix(ci): pin the Rust nightly version

Temporary fix until the `ring` build issue is fixed.

- briansmith/ring#1469
- rust-lang/rust#95267

.github/actions/run-fixtures-test/action.yml

@@ -17,7 +17,7 @@ runs:
       uses: actions-rs/toolchain@v1
       with:
         profile: minimal
-        toolchain: nightly
+        toolchain: nightly-2022-03-22
         override: true
 
     - name: Install git-cliff

.github/workflows/ci.yml

@@ -37,7 +37,7 @@ jobs:
         uses: actions-rs/toolchain@v1
         with:
           profile: minimal
-          toolchain: nightly
+          toolchain: nightly-2022-03-22
           override: true
       - name: Checkout
         if: github.event_name != 'pull_request'
@@ -68,7 +68,7 @@ jobs:
       - name: Install toolchain
         uses: actions-rs/toolchain@v1
         with:
-          toolchain: nightly
+          toolchain: nightly-2022-03-22
           profile: minimal
           components: clippy
           override: true
@@ -87,7 +87,7 @@ jobs:
       - name: Install toolchain
         uses: actions-rs/toolchain@v1
         with:
-          toolchain: nightly
+          toolchain: nightly-2022-03-22
           profile: minimal
           components: rustfmt
           override: true