update terraform runner version

Author: OlamideOl1

.github/workflows/terraform.yaml

@@ -5,7 +5,7 @@ on:
 jobs:
   checkfmt:
     name: Format
-    runs-on: ubuntu-18.04
+    runs-on: ubuntu-latest
     steps:
     - name: Checkout repository
       uses: actions/checkout@v2
@@ -18,7 +18,7 @@ jobs:
 
   validate:
     name: Validate
-    runs-on: ubuntu-18.04
+    runs-on: ubuntu-latest
     steps:
     - name: Checkout repository
       uses: actions/checkout@v2
@@ -31,7 +31,7 @@ jobs:
 
   docs:
     name: Docs
-    runs-on: ubuntu-18.04
+    runs-on: ubuntu-latest
     steps:
     - name: Checkout repository
       uses: actions/checkout@v2
@@ -46,7 +46,7 @@ jobs:
 
   lint:
     name: Lint
-    runs-on: ubuntu-18.04
+    runs-on: ubuntu-latest
     steps:
     - name: Checkout repository
       uses: actions/checkout@v2