[newlib-cygwin/main] Cygwin: CI: bump actions/checkout from v3 to v5

[Jon Turney]

https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=2abd244aac7424259fb05a8af6c242d2a7a21b66

commit 2abd244aac7424259fb05a8af6c242d2a7a21b66
Author: Johannes Schindelin <johannes.schindelin@gmx.de>
Date:   Sat Aug 30 20:40:58 2025 +0200

    Cygwin: CI: bump actions/checkout from v3 to v5
    
    There were two major version bumps:
    
    - v3 -> v4: new runs using Node.JS v20 instead of v16
    - v4 -> v5: now runs using Node.JS v24 instead of v20
    
    Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

Diff:
---
 .github/workflows/cygwin.yml | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/.github/workflows/cygwin.yml b/.github/workflows/cygwin.yml
index 49d3d89f2..c97e2f21c 100644
--- a/.github/workflows/cygwin.yml
+++ b/.github/workflows/cygwin.yml
@@ -24,7 +24,7 @@ jobs:
       HAS_SSH_KEY: ${{ secrets.SSH_KEY != '' }}
 
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v5
 
     # install build tools
     - name: Install build tools
@@ -111,7 +111,7 @@ jobs:
       run: |
         icacls . /inheritance:r
         icacls . /grant Administrators:F
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v5
 
     # install cygwin and build tools
     - name: Install Cygwin