Bump version to 2.61.0-dev #4161

Job	Run time
Run Guideline Recategorization tests	16s
Run release tests	17s
Prepare supported CodeQL environment matrix	7s
Run analysis report tests (2.21.4, codeql-cli/v2.21.4, codeql-bundle-v2.21.4)	5m 46s
	6m 26s

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