ci: Disable builds on forks (#6589)

Signed-off-by: Yuan Tang <terrytangyuan@gmail.com>

.github/workflows/changelog.yaml

@@ -7,6 +7,7 @@ on:
       - "!v0.0.0"
 jobs:
   generate_changelog:
+    if: github.repository == 'argoproj/argo-workflows'
     runs-on: ubuntu-latest
     name: Generate changelog
     steps:

.github/workflows/gh-pages.yaml

@@ -7,6 +7,7 @@ on:
 
 jobs:
   deploy:
+    if: github.repository == 'argoproj/argo-workflows'
     runs-on: ubuntu-20.04
     steps:
       - uses: actions/checkout@v2

.github/workflows/release.yaml

@@ -15,6 +15,7 @@ defaults:
 jobs:
   build-linux-amd64:
     name: Build & push linux/amd64
+    if: github.repository == 'argoproj/argo-workflows'
     runs-on: ubuntu-20.04
     strategy:
       matrix:
@@ -80,6 +81,7 @@ jobs:
 
   build-linux-arm64:
     name: Build & push linux/arm64
+    if: github.repository == 'argoproj/argo-workflows'
     runs-on: ubuntu-20.04
     strategy:
       matrix:
@@ -150,6 +152,7 @@ jobs:
 
   build-windows:
     name: Build & push windows
+    if: github.repository == 'argoproj/argo-workflows'
     runs-on: windows-2019
     steps:
       - uses: actions/checkout@v2
@@ -189,6 +192,7 @@ jobs:
 
   push-linux-amd64-images:
     name: Push manifest with linux/amd64
+    if: github.repository == 'argoproj/argo-workflows'
     runs-on: ubuntu-20.04
     needs: [ build-linux-amd64 ]
     steps:
@@ -232,6 +236,7 @@ jobs:
 
   push-images:
     name: Push manifest with all images
+    if: github.repository == 'argoproj/argo-workflows'
     runs-on: ubuntu-20.04
     needs: [ build-linux-arm64, build-windows, push-linux-amd64-images ]
     steps:
@@ -279,6 +284,7 @@ jobs:
           done
   test-images-linux-amd64:
     name: Try pulling linux/amd64
+    if: github.repository == 'argoproj/argo-workflows'
     runs-on: ubuntu-20.04
     needs: [ push-images ]
     strategy:
@@ -316,6 +322,7 @@ jobs:
 
   test-images-windows:
     name: Try pulling windows
+    if: github.repository == 'argoproj/argo-workflows'
     runs-on: windows-2019
     needs: [ push-images ]
     steps:
@@ -350,6 +357,7 @@ jobs:
 
   publish-release:
     runs-on: ubuntu-20.04
+    if: github.repository == 'argoproj/argo-workflows'
     needs: [ push-images, test-images-linux-amd64, test-images-windows ]
     env:
       NODE_OPTIONS: --max-old-space-size=4096

.github/workflows/snyk.yml

@@ -4,6 +4,7 @@ on:
     - cron: "30 2 * * *"
 jobs:
   security:
+    if: github.repository == 'argoproj/argo-workflows'
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@master