tools: release.sh: produce only SHA256 hashes

Both MD5 and SHA-1 shouldn't be relied upon since long.

Change-Id: I0dea92fbf0f68b900c0d3a314fb3956d08ba0d48
Signed-off-by: Paul Fertser <fercerpav@gmail.com>
Reviewed-on: http://openocd.zylin.com/3949
Tested-by: jenkins

tools/release.sh

@@ -102,7 +102,7 @@ do_stage() {
 	for EXT in tar.gz tar.bz2 zip; do
 		local FILE="${PACKAGE_RELEASE}.${EXT}"
 		# create archive signatures
-		for HASH in md5 sha1; do
+		for HASH in sha256; do
 			echo "sign: ${FILE}.${HASH}"
 			${HASH}sum "${FILE}" > "archives/${FILE}.${HASH}"
 		done