sdl2-compat: actions: fixed typo.

SDL Commits
1 
From b48726009caa0cdddc7490f2ba62b7a96f4f3094 Mon Sep 17 00:00:00 2001
From: "Ryan C. Gordon" <[EMAIL REDACTED]>
Date: Tue, 29 Nov 2022 21:51:31 -0500
Subject: [PATCH] actions: fixed typo.

---
 .github/workflows/main.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 4987c8d..9b79bfb 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -27,6 +27,6 @@ jobs:
         ref: main
         path: SDL3
     - name: Configure CMake
-      run: cmake -DSDL3_INCLUDE_DIR="${{ github.workspace }}/SDL3/include" -B build ${{ matrix.platform.flags }}
+      run: cmake -DSDL3_INCLUDE_DIRS="${{ github.workspace }}/SDL3/include" -B build ${{ matrix.platform.flags }}
     - name: Build
       run: cmake --build build/