Upgrade actions to latest

Author: Ehsan M. Kermani

.github/workflows/ci.yml

@@ -12,10 +12,10 @@ env:
 jobs:
   style:
     name: Style Check
-    runs-on: ubuntu-18.04
+    runs-on: ubuntu-latest
     steps:
       - name: Checkout
-        uses: actions/checkout@v2
+        uses: actions/checkout@v3
 
       - name: Install Rust
         uses: actions-rs/toolchain@v1
@@ -32,9 +32,9 @@ jobs:
           args: --all -- --check
 
   build:
-    runs-on: ubuntu-18.04
+    runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v3
       - name: Install LLVM
         run: |
           wget https://apt.llvm.org/llvm.sh

.github/workflows/gh-pages.yml

@@ -7,9 +7,9 @@ on:
 
 jobs:
   deploy:
-    runs-on: ubuntu-18.04
+    runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v3
       - name: Setup mdBook
         uses: peaceiris/actions-mdbook@v1
         with: