setup-sdl: Include MSYSTEM in hash

SDL Commits
1 
From 5cda0f9aaad8d4fbcb663267bd481e3de9460e25 Mon Sep 17 00:00:00 2001
From: Anonymous Maarten <[EMAIL REDACTED]>
Date: Fri, 30 Jun 2023 23:54:11 +0200
Subject: [PATCH] Include MSYSTEM in hash

---
 packed/index.js | 1 +
 src/main.ts     | 1 +
 2 files changed, 2 insertions(+)

diff --git a/packed/index.js b/packed/index.js
index 33e62f5..1cb78e2 100644
--- a/packed/index.js
+++ b/packed/index.js
@@ -268,6 +268,7 @@ function calculate_state_hash(args) {
         "LIBPATH",
         "CMAKE_PREFIX_PATH",
         "CMAKE_TOOLCHAIN_FILE",
+        "MSYSTEM",
         "PKG_CONFIG_PATH",
     ];
     var env_state = [];
diff --git a/src/main.ts b/src/main.ts
index 4128d1b..6291494 100644
--- a/src/main.ts
+++ b/src/main.ts
@@ -165,6 +165,7 @@ function calculate_state_hash(args: {
     "LIBPATH",
     "CMAKE_PREFIX_PATH",
     "CMAKE_TOOLCHAIN_FILE",
+    "MSYSTEM",
     "PKG_CONFIG_PATH",
   ];
   const env_state: string[] = [];