remove linux/ppc64le

We saw the following error during `go mod tidy`
```
#52 60.57 endlessh-go imports
#52 60.57 	github.com/golang/glog: github.com/golang/glog@v1.0.0: Get "https://proxy.golang.org/github.com/golang/glog/@v/v1.0.0.zip": net/http: TLS handshake timeout
#52 60.57 endlessh-go imports
#52 60.57 	github.com/pierrre/geohash: github.com/pierrre/geohash@v1.0.0: Get "https://proxy.golang.org/github.com/pierrre/geohash/@v/v1.0.0.zip": net/http: TLS handshake timeout
```

.github/workflows/docker-hub-build-push-on-release.yml

@@ -5,7 +5,7 @@ on:
     types: # This configuration does not affect the page_build event above
       - created
 env:
-  PLATFORMS: "linux/amd64,linux/386,linux/arm64,linux/arm/v7,linux/arm/v6,linux/ppc64le,linux/s390x"
+  PLATFORMS: "linux/amd64,linux/386,linux/arm64,linux/arm/v7,linux/arm/v6,linux/s390x"
   
 jobs:
   build_and_push: