Fix parameters passed for GCS URL generation

[balasankarc]

When GCP support was originally added in #3481, the parameters were response_disposition and content_type. When it was refactored in #4251, the headers for GCS were mistakenly changed and expanded.

These parameters get used by generate_signed_url method defined in https://github.com/googleapis/python-storage/blob/a8109e0/google/cloud/storage/blob.py#L463, through
https://github.com/jschneier/django-storages/blob/758ad6f/storages/backends/gcloud.py#L350

This PR ensures only the supported parameters are passed to that function call.

closes #6917

[balasankarc]

@bmbouter I confirmed this changes fixes the issue mentioned in #6917. Can you please help me find a reviewer for the PR? Thanks.

[ggainey]

Minor nitpick

[ggainey]

Minor nit - can we get this on its own line? :)

[mdellweg]

I cannot tell whether this is the right thing to do, and we neither support nor test GCS.
(Some time ago we failed setting up the corresponding test runner in a deterministic way and abandoned the idea.)
So I am going to approve this change with the disclaimer that this does not change our stance on the supported storage backends as stated here:
https://pulpproject.org/pulpcore/docs/admin/reference/settings/#storages

Thank you for your effort.

[ggainey]

I'm going to withdraw the change-request - doesn't affect anythiing other than "aesthetics", and not worth holding up the PR. Approving, while seconding @mdellweg 's commentary.

[balasankarc]

@ggainey @bmbouter Is a minor version release (3.90.0) planned soon? If not, would it be possible to have a patch version for 3.89.x with this fix released?

[patchback]

Backport to 3.89: 💚 backport PR created

✅ Backport PR branch: patchback/backports/3.89/fc99a60a59398909ebab38ffe9e3f2196f9c9855/pr-6940

Backported as #6956

🤖 @patchback
I'm built with octomachinery and
my source is open — https://github.com/sanitizers/patchback-github-app.

[ggainey]

@ggainey @bmbouter Is a minor version release (3.90.0) planned soon? If not, would it be possible to have a patch version for 3.89.x with this fix released?

I'll backport to 3.89 and get a z-release out shortly - that way we don't have to wait for a new Y

[ggainey]

@ggainey @bmbouter Is a minor version release (3.90.0) planned soon? If not, would it be possible to have a patch version for 3.89.x with this fix released?

I'll backport to 3.89 and get a z-release out shortly - that way we don't have to wait for a new Y

https://pypi.org/project/pulpcore/3.89.1/