Fix Verifying checksum step for Windows

Author: socheatsok78

action.sh

@@ -96,12 +96,12 @@ if [ ! -d "${FLUTTER_RUNNER_TOOL_CACHE}" ]; then
 	then
 		if [[ -n "${FLUTTER_RELEASE_SHA256}" ]]; then
 			echo -n "Verifying checksum "
-			if [[ $OS == "linux" ]]
+			if [[ $OS == "macos" ]]
 			then
-				echo "${FLUTTER_RELEASE_SHA256} ${DOWNLOAD_PATH}" | sha256sum -c -
-			else
 				# Note: on macOS put 2 spaces between the hash and the filename
 				echo "${FLUTTER_RELEASE_SHA256}  ${DOWNLOAD_PATH}" | shasum -a 256 -c -
+			else
+				echo "${FLUTTER_RELEASE_SHA256} ${DOWNLOAD_PATH}" | sha256sum -c -
 			fi
 		fi
 	else