Update github CI to latest version (#181)

Author: Emilia Hane

.github/workflows/build.yml

@@ -6,7 +6,7 @@ jobs:
   cargo-fmt:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v3
       - name: Get latest version of stable rust
         run: rustup update stable
       - name: Check formatting with cargofmt
@@ -15,7 +15,7 @@ jobs:
     runs-on: ubuntu-latest
     needs: cargo-fmt
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v3
       - name: Get latest version of stable rust
         run: rustup update stable
       - name: Install protobuf compiler for the libp2p-core dependency
@@ -26,7 +26,7 @@ jobs:
     runs-on: ubuntu-latest
     needs: cargo-fmt
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v3
       - name: Get latest version of stable rust
         run: rustup update stable
       - name: Run tests in release
@@ -37,7 +37,7 @@ jobs:
       image: rust
     needs: cargo-fmt
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v3
       - name: Get latest version of stable rust
         run: rustup update stable
       - name: Install protobuf compiler for the libp2p-core dependency
@@ -50,7 +50,7 @@ jobs:
     container:
       image: rust
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v3
       - name: Get latest version of stable rust
         run: rustup update stable
       - name: Check rustdoc links