Only one auto-merge per hour can cause latency for new package versions

[dbeatty10]

Potentially related to #1484

Current functionality

A script runs at the top of every hour and looks for newly released package versions. When a new tag is added to a GitHub repo that is listed on the dbt Package Hub, a pull request is automatically opened within this (hub.getdbt.com) repo. These pull requests are somehow merged automatically.

The problem is that only one pull request is merged per hour. If multiple pull requests are opened within a single hour, then duplicate pull requests will be opened every subsequent hour until all PRs are able to merge.

Desired functionality

Do at least one of the following:

1. Merge multiple PRs per hour, or
2. Open a single PR containing all new package versions (rather than separate PRs)

Either one of these options should solve the problems listed above.

Also, it would be nice if 100% duplicate PRs weren't opened. Although related, it could be a separate issue opened within https://github.com/dbt-labs/hubcap. It could be accomplished by naming the PR or the branch using a md5 hash of the git diff or something similar.

Implementation

The 2nd option would actually be implemented within https://github.com/dbt-labs/hubcap rather than this repo. 👈 I lean towards trying this one first.

The 1st option could theoretically be accomplished within this repo, but I don't know what is dictating only one PR merge per hour -- it might be something with these GitHub Actions, but it might be something else.

[dbeatty10]

Resolved by dbt-labs/hubcap#154

Confirmed to work by #2074 (two different packages updated by the same pull request).

#2071 shows an example of two different versions of the same package within one pull request.