Scope some workflows to the main repository

It makes little sense to run these GitHub workflows anywhere but in the
`git-for-windows` org; In fact, it may cause mayhem if attempting to run
them elsewhere, so let's prevent that footgun.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

Author: dscho

.github/workflows/break-pacman-upload-lease.yml

@@ -6,6 +6,7 @@ on:
 
 jobs:
   break-lease:
+    if: github.event.repository.owner.login == 'git-for-windows'
     runs-on: ubuntu-latest
     steps:
       - name: Clone build-extra

.github/workflows/build-and-deploy.yml

@@ -36,6 +36,7 @@ env:
 
 jobs:
   build:
+    if: github.event.repository.owner.login == 'git-for-windows'
     runs-on: ${{ github.event.inputs.architecture == 'aarch64' && fromJSON('["Windows", "ARM64"]') || 'windows-latest' }}
     steps:
       - uses: actions/checkout@v4

.github/workflows/open-pr.yml

@@ -24,6 +24,7 @@ env:
 
 jobs:
   open-pr:
+    if: github.event.repository.owner.login == 'git-for-windows'
     runs-on: windows-latest
     steps:
       - name: Determine REPO

.github/workflows/release-git.yml

@@ -25,6 +25,7 @@ env:
 jobs:
   setup:
     runs-on: ubuntu-latest
+    if: github.event.repository.owner.login == 'git-for-windows'
     outputs:
       display-version: ${{ steps.bundle-artifacts.outputs.display-version }}
       tag-name: ${{ steps.bundle-artifacts.outputs.tag-name }}

.github/workflows/updpkgsums.yml

@@ -24,6 +24,7 @@ env:
 
 jobs:
   updpkgsums:
+    if: github.event.repository.owner.login == 'git-for-windows'
     runs-on: windows-latest
     steps:
       - uses: actions/checkout@v4