stage_external_sources fails after update from dbt 1.4.5 to 1.7.10 and dbt-redshift 1.4.0 to 1.7.7

[lgwoodmark]

Describe the bug

When running stage_external_sources for dbt-core 1.7.10 and dbt-redshift 1.7.7, the macro fails, claiming an error in redshift__refresh_external_table when running from lines 17 on, claiming that partition is a string object. This does not happen in dbt 1.4.5 and dbt-redshift 1.4.0, which was out previous version before updating.

Steps to reproduce

None of the source definitions containing a partitions block work anymore.

partitions:
  - name: load_date
    data_type: date
    vals:
      macro: dbt.dates_in_range
      args:
        start_date_str: '2022-01-01'
        end_date_str: "{{ modules.datetime.date.today().strftime('%Y-%m-%d') }}"
        in_fmt: "%Y-%m-%d"
        out_fmt: "%Y-%m-%d"
    path_macro: dbt_external_tables.year_month_day

--->

Expected results

Running stage_external_sources works as it did before the update.

Actual results

The script errors out with Compilation Error 'str object' has no attribute 'vals'

Screenshots and log output

$ dbt run-operation stage_external_sources -t lab
22:23:11  Running with dbt=1.7.10
22:23:12  Registered adapter: redshift=1.7.7
22:24:32  Found 1401 models, 2277 tests, 6 seeds, 11 operations, 4 analyses, 840 sources, 3 exposures, 0 metrics, 835 macros, 0 groups, 0 semantic models
22:24:34  1 of 1 START external xxx.yyy
22:24:35  Encountered an error while running operation: Compilation Error
  'str object' has no attribute 'vals'

  > in macro refresh_external_table (macros\common\refresh_external_table.sql)
  > called by macro redshift__get_external_build_plan (macros\plugins\redshift\get_external_build_plan.sql)
  > called by macro get_external_build_plan (macros\common\get_external_build_plan.sql)
  > called by macro stage_external_sources (macros\common\stage_external_sources.sql)
  > called by <Unknown>

System information

The contents of your packages.yml file:

packages:

• package: dbt-labs/dbt_external_tables
  version: "0.11.1"
• package: dbt-labs/dbt_utils
  version: "1.1.1"
• package: dbt-labs/logging
  version: "0.8.0"
• package: dbt-labs/codegen
  version: "0.10.0"
• git: "https://github.com/calogica/dbt-date.git"
  revision: "0.10.1"

Which database are you using dbt with?

• redshift
• snowflake
• other (specify: ____________)

The output of dbt --version:

Core:
  - installed: 1.7.10
  - latest:    1.9.1  - Update available!

  Your version of dbt-core is out of date!
  You can find instructions for upgrading here:
  https://docs.getdbt.com/docs/installation

Plugins:
  - postgres: 1.7.10 - Update available!
  - redshift: 1.7.7  - Update available!

  At least one plugin is out of date or incompatible with dbt-core.
  You can find instructions for upgrading here:
  https://docs.getdbt.com/docs/installation

The operating system you're using:
Windows 11 Enterprise 24H2

The output of python --version:
Python 3.9.13