Use restic 0.13.1 (#604) (#628)

/cherry-pick

Signed-off-by: 1gtm <1gtm@appscode.com>

Co-authored-by: lgtm <1gtm@users.noreply.github.com>

Author: Emruz Hossain

Makefile

@@ -42,7 +42,7 @@ else
 	endif
 endif
 
-RESTIC_VER       := 0.13.0
+RESTIC_VER       := 0.13.1
 
 ###
 ### These variables should not need tweaking.