build: disable docker builds on PRs & add missing dockerfile changes

Signed-off-by: Anagh Kumar Baranwal <6824881+darthShadow@users.noreply.github.com>

.github/workflows/build_publish_docker_image.yml

@@ -1,6 +1,6 @@
 ---
 # Github Actions release for rclone
-# -*- compile-command: "yamllint -f build_publish_docker_image.yml" -*-
+# -*- compile-command: "yamllint -f parsable build_publish_docker_image.yml" -*-
 
 name: Build & Push Docker Images
 
@@ -11,7 +11,6 @@ on:
       - '**'
     tags:
       - '**'
-  pull_request:
   workflow_dispatch:
     inputs:
       manual:
@@ -21,7 +20,7 @@ on:
 
 jobs:
   build-image:
-    if: inputs.manual || (github.repository == 'rclone/rclone' && (github.event_name != 'pull_request' || github.event.pull_request.head.repo.full_name != github.event.pull_request.base.repo.full_name))
+    if: inputs.manual || (github.repository == 'rclone/rclone' && github.event_name != 'pull_request')
     timeout-minutes: 60
     strategy:
       fail-fast: false
@@ -192,6 +191,7 @@ jobs:
           if-no-files-found: error
 
   merge-image:
+    name: Merge & Push Final Docker Image
     runs-on: ubuntu-24.04
     needs:
       - build-image

Dockerfile

@@ -1,19 +1,47 @@
 FROM golang:alpine AS builder
 
-COPY . /go/src/github.com/rclone/rclone/
+ARG CGO_ENABLED=0
+
 WORKDIR /go/src/github.com/rclone/rclone/
 
-RUN apk add --no-cache make bash gawk git
-RUN \
-  CGO_ENABLED=0 \
-  make
-RUN ./rclone version
+RUN echo "**** Set Go Environment Variables ****" && \
+    go env -w GOCACHE=/root/.cache/go-build
+
+RUN echo "**** Install Dependencies ****" && \
+    apk add --no-cache \
+        make \
+        bash \
+        gawk \
+        git
+
+COPY go.mod .
+COPY go.sum .
+
+RUN echo "**** Download Go Dependencies ****" && \
+    go mod download -x
+
+RUN echo "**** Verify Go Dependencies ****" && \
+    go mod verify
+
+COPY . .
+
+RUN --mount=type=cache,target=/root/.cache/go-build,sharing=locked \
+    echo "**** Build Binary ****" && \
+    make
+
+RUN echo "**** Print Version Binary ****" && \
+    ./rclone version
 
 # Begin final image
 FROM alpine:latest
 
-RUN apk --no-cache add ca-certificates fuse3 tzdata && \
-  echo "user_allow_other" >> /etc/fuse.conf
+RUN echo "**** Install Dependencies ****" && \
+    apk add --no-cache \
+        ca-certificates \
+        fuse3 \
+        tzdata && \
+    echo "Enable user_allow_other in fuse" && \
+    echo "user_allow_other" >> /etc/fuse.conf
 
 COPY --from=builder /go/src/github.com/rclone/rclone/rclone /usr/local/bin/