fix: pre-commit.ci error

[shmpwk]

Description

Resolve pre-commit.ci error

flake8 ros...............................................................Failed
- hook id: flake8-ros
- exit code: 1

system/diagnostic_graph_aggregator/script/dump.py:34:37: E231 missing whitespace after ':'
        line = map(lambda v, w: f"{v:{w}}", line, widths)
                                    ^
1     E231 missing whitespace after ':'

https://results.pre-commit.ci/run/github/438106587/1714613670.K3nwJB10QBmgl0y_WPd6RQ

Tests performed

Not applicable.

Effects on system behavior

Not applicable.

Pre-review checklist for the PR author

The PR author must check the checkboxes below when creating the PR.

• I've confirmed the contribution guidelines.
• The PR follows the pull request guidelines.

In-review checklist for the PR reviewers

The PR reviewers must check the checkboxes below before approval.

• The PR follows the pull request guidelines.

Post-review checklist for the PR author

The PR author must check the checkboxes below before merging.

• There are no open discussions or they are tracked via tickets.

After all checkboxes are checked, anyone who has write access can merge the PR.

[shmpwk]

This should be fixed in autowarefoundation

[shmpwk]

This will be fixed in autowarefoundation#6715, but we'd like to merge this earlier.