[llvm] [workflows] Only run code formatter on the main branch (PR #80348)

[Tom Stellard via llvm-commits]

https://github.com/tstellar created https://github.com/llvm/llvm-project/pull/80348

Modifying a cherry-picked patch to fix code formatting issues can be risky, so we don't typically do this.  Therefore, it's not necessary to run this job on the release branches.

>From a818452326d1d083e726d6889544387a6dad7bd9 Mon Sep 17 00:00:00 2001
From: Tom Stellard <tstellar at redhat.com>
Date: Thu, 1 Feb 2024 13:45:57 -0800
Subject: [PATCH] [workflows] Only run code formatter on the main branch

Further modifying a cherry-picked patch to fix code formatting issues
can be risky, so we don't typically do this.  Therefore, it's not
necessary to run this job on the release branches.
---
 .github/workflows/pr-code-format.yml | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/.github/workflows/pr-code-format.yml b/.github/workflows/pr-code-format.yml
index 5223089ee8a93..c8fd541fd34db 100644
--- a/.github/workflows/pr-code-format.yml
+++ b/.github/workflows/pr-code-format.yml
@@ -1,5 +1,8 @@
 name: "Check code formatting"
 on: pull_request_target
+  branches:
+    - main
+
 permissions:
   pull-requests: write