fix: Support stdin on Windows when possible

This add support for stdin input from Windows from Python 3.12 onwards.

svgcheck/run.py

@@ -110,11 +110,14 @@ def main():
     if len(args) < 1:
         # delete_on_close was introduced in Python 3.12
         delete_on_close = {"delete_on_close": False} if sys.version_info >= (3, 12) else {}
+
         with tempfile.NamedTemporaryFile(mode="w+b", **delete_on_close) as tmp_file:
             data = sys.stdin.buffer.read()
             tmp_file.write(data)
             if sys.version_info >= (3, 12):
                 tmp_file.close()
+            elif sys.platform.lower().startswith("win"):
+                sys.exit("Stdin is only supported on Windows with Python 3.12 and above.")
             else:
                 # Prior to Python 3.12 file is deleted as soon as it's closed
                 tmp_file.seek(0)

svgcheck/test.py

@@ -67,6 +67,10 @@ def test_clear_cache(self):
                       None, None)
         self.assertFalse(os.path.exists('Temp/cache/reference.RFC.1847.xml'))
 
+    @unittest.skipIf(
+        sys.platform.lower().startswith("win") and sys.version_info < (3, 12),
+        "Skip on Windows with Python version less than 3.12."
+    )
     def test_stdin(self):
         process = subprocess.Popen([sys.executable, test_program],
                                    stdin=subprocess.PIPE,