[DATALAD RUNCMD] Migrate configuration to use SHA256E backend

=== Do not change lines below ===
{
 "chain": [],
 "cmd": "sed -i -e s,MD5E,SHA256E,g .gitattributes",
 "dsid": "02143555-36b6-4abb-b455-1a6ba625f612",
 "exit": 0,
 "extra_inputs": [],
 "inputs": [],
 "outputs": [],
 "pwd": "."
}
^^^ Do not change lines above ^^^

.gitattributes

@@ -1,3 +1,3 @@
-* annex.backend=MD5E
+* annex.backend=SHA256E
 **/.git* annex.largefiles=nothing
 * annex.largefiles=((mimeencoding=binary)and(largerthan=0))