Specify SDL3 commit to build

.github/workflows/build.yml

@@ -1,7 +1,12 @@
 name: Build Native
 on:
   workflow_dispatch:
-    inputs: {}
+    inputs:
+      sdl_ref:
+        description: SDL3 commit/branch/tag to build
+        required: true
+        default: main
+        type: string
 #  schedule:
 #    - cron: '0 0 * * *'
 env:
@@ -29,7 +34,7 @@ jobs:
       - uses: actions/checkout@v4
         with:
           repository: 'libsdl-org/SDL'
-          ref: 'main'
+          ref: ${{ inputs.sdl_ref }}
 
       - uses: actions/checkout@v4
         with:
@@ -94,7 +99,7 @@ jobs:
       - uses: actions/checkout@v4
         with:
           repository: 'libsdl-org/SDL'
-          ref: 'main'
+          ref: ${{ inputs.sdl_ref }}
 
       - uses: actions/checkout@v4
         with:
@@ -137,7 +142,7 @@ jobs:
       - uses: actions/checkout@v4
         with:
           repository: 'libsdl-org/SDL'
-          ref: 'main'
+          ref: ${{ inputs.sdl_ref }}
 
       - uses: actions/checkout@v4
         with: