Update build-docker.yml

.github/workflows/build-docker.yml

@@ -15,21 +15,22 @@ on:
         required: false
         type: string
 
+env:
+  LTHN_TAG: ${{ inputs.chain-network == 'testnet' && 'testnet' || 'latest' }}
+
 jobs:
   build:
     runs-on: ${{ matrix.runner }}
-    env:
-      LTHN_TAG: ${{ inputs.chain-network == 'testnet' && 'testnet' || 'latest' }}
     strategy:
       matrix:
         include:
           - arch: amd64
             runner: ubuntu-latest
-            tag: ${{ env.LTHN_TAG }}-amd64
+            tag: "${{ env.LTHN_TAG }}-amd64"
             platform: linux/amd64
           - arch: arm64
             runner: ubuntu-arm
-            tag: ${{ env.LTHN_TAG }}-arm64
+            tag: "${{ env.LTHN_TAG }}-arm64"
             platform: linux/arm64
     steps:
       - uses: actions/checkout@v4
@@ -55,8 +56,6 @@ jobs:
   manifest:
     needs: build
     runs-on: ubuntu-latest
-    env:
-      LTHN_TAG: ${{ inputs.chain-network == 'testnet' && 'testnet' || 'latest' }}
     steps:
       - name: Log in to DockerHub
         uses: docker/login-action@v3