Update devcontainer-freertos-nxp.yaml

Only get the version from the first line.
Allows ability for the docker to have labels.

Author: networkfusion

.github/workflows/devcontainer-freertos-nxp.yaml

@@ -33,7 +33,7 @@ jobs:
     - name: Get container version
       shell: pwsh
       run: |
-        $dockerfileContent = Get-Content("${{ env.CONTAINER_VERSION_FILE }}")
+        $dockerfileContent = Get-Content("${{ env.CONTAINER_VERSION_FILE }}") -First 1
         $dockerfileContent -match '(?<=\:)(?:[v]\d+.\d+)'
         $containerVersion = $Matches[0].ToString()
         echo "GCR_VERSION=$containerVersion" | Out-File -FilePath $Env:GITHUB_ENV -Encoding utf-8 -Append