Move the pin to ata-validator 1.7.4

[mertcanaltin]

The report has been showing 23 errored draft-07 tests for ata. They are not a
draft-07 problem, they are one bug: 1.7.1 drops $id when it sits next to
$ref in a draft-07 document. Draft-07 ignores keywords beside $ref, so
normalisation drops them and $id goes too. That is right for evaluation and
wrong for registration, because the document then has no name the registry can
address it by, and every remote reference to it errors. 1.7.2 fixed it, and the
pin here has been behind since.

Measured with bowtie suite against a locally built image of this branch:

dialect	on 1.7.1	on 1.7.4
draft-07	927 tests, 23 errored	927 tests, 0 errored, 0 failed
Draft 2020-12	1299 tests, 1 failed	1299 tests, 1 failed

The remaining 2020-12 failure is $vocabulary, which ata does not implement.
That is unchanged and not what this touches.

Not in here: declaring https://json-schema.org/v1. Bowtie learned the dialect
in bowtie-json-schema/bowtie#3067, but the workflow pins in this repo still
point at bowtie commits from before it, and that version does not skip a
dialect it does not know, it raises:

File "bowtie/_core.py", line 305, in from_dict
    dialects=frozenset(Dialect.from_str(each) for each in dialects),
File "bowtie/_core.py", line 188, in from_str
    return by_uri[url]
KeyError: <URL https://json-schema.org/v1>

That is startup, so ata would drop out of the report entirely rather than
gaining a dialect. It waits until the pins move. For what it is worth I ran v1
against bowtie main with the URI declared, and it is 1133 tests with 1 failure,
which is bowtie-json-schema/bowtie#3068 rather than anything here.