Fix bug in dependency update workflow.

[jonsimantov]

Description

Provide details of the change, and generalize the change in the PR title above.

Fix a bug in the Python script that outputs the logfile of dependency changes. Also make the workflow script a little more robust in the case where the logfile doesn't exist or is malformed (it should still create the PR, just without the details in the description).

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Testing

Describe how you've tested these changes. Link any manually triggered Integration tests or CPP binary SDK Packaging Github Action workflows, if applicable.

https://github.com/firebase/firebase-cpp-sdk/actions/runs/1284791796

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Type of Change

Place an x the applicable box:

• Bug fix. Add the issue # below if applicable.
• New feature. A non-breaking change which adds functionality.
• Other, such as a build process or documentation change.

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Notes

• Bug fixes and feature changes require an update to the Release Notes section of release_build_files/readme.md.
• Read the contribution guidelines CONTRIBUTING.md.
• Changes to the public API require an internal API review. If you'd like to help us make Firebase APIs better, please propose your change in a feature request so that we can discuss it together.

[github-actions]

❌  Integration test FAILED

Requested by @jonsimantov on commit 9e702bf
Last updated: Tue Sep 28 19:54 PDT 2021
View integration test log & download artifacts

Failures	Configs
admob	[BUILD] [ERROR] [Android] [macos]
analytics	[BUILD] [ERROR] [Android] [macos]
auth	[BUILD] [ERROR] [Android] [macos]
functions	[BUILD] [ERROR] [Android] [macos]

Add flaky tests to go/fpl-cpp-flake-tracker