fix a bug in which a closing parenthesis in @graphql directive failed to parse as json

[imor]

What kind of change does this PR introduce?

Bug fix

What is the current behavior?

If a comment directive had a closing parenthesis, it failed to parse as valid json. E.g. comment on column table.column is e'@graphql({"description": "column description)"})'; would fail with error invalid input syntax for type json

What is the new behavior?

The comment directive parses as json successfully.

Additional context

The parsing failed because the regex in graphql.comment_directive function had a non-greedy match (.+?). This terminated the search for an ending parenthesis early, resulting in an invalid json string. E.g. the following statement:

select regexp_match(
	'@graphql({"description": "column description)"})',
	'@graphql\((.+?)\)'
);

returns {"{\"description\": \"column description"}. While the fixed regexp correctly returns {"{\"description\": \"column description)\"}"}.