Update check_release for bikeshed changes

Update line numbers and the date pattern we search for in check_release
to match the newly bikeshed flavoured specification document.

Signed-off-by: Joshua Lock <[email protected]>

Author: joshuagl

check_release.py

@@ -30,11 +30,11 @@
 
 SPEC_NAME = "tuf-spec.md"
 
-LAST_MODIFIED_PATTERN = "Last modified: **%d %B %Y**\n"
-LAST_MODIFIED_LINENO = 3
+LAST_MODIFIED_PATTERN = "Date: %Y-%m-%d\n"
+LAST_MODIFIED_LINENO = 6
 
 VERSION_PATTERN = r"^Version: \*\*(\d*)\.(\d*)\.(\d*)\*\*$"
-VERSION_LINENO = 5
+VERSION_LINENO = 19
 
 class SpecError(Exception):
   """Common error message part. """