Remove linux/arm/v7 platform

Remove linux/arm/v7 platform due to lack of use, and replacement by linux/arm64 platform.

Signed-off-by: Alex Ellis <alexellis2@gmail.com>

Author: alexellis

.github/workflows/publish.yaml

@@ -42,7 +42,7 @@ jobs:
           faas-cli publish
           --extra-tag ${{ github.sha }}
           --build-arg GO111MODULE=on
-          --platforms linux/arm/v7,linux/arm64,linux/amd64
+          --platforms linux/arm64,linux/amd64
 
       - name: Publish amd64-only functions
         run: >