refactor: Use Duration dataclass #311

Job	Run time
setup	4s
Hello World	1m 5s
Step with Retry	1m 2s
Basic Step	1m 2s
Multiple Wait	56s
Step with Name	1m 3s
Parallel Operations	57s
Callback	1m 2s
Map Operations	1m 3s
Run in Child Context	57s
Steps with Retry	51s
Run in Child Context Large Data	1m 3s
Logger Example	1m 2s
Block Example	1m 2s
Map with Max Concurrency	1m 3s
Wait State	1m 5s
Simple Execution	1m 11s
Wait for Condition	59s
Parallel with Wait	55s
Map with Failure Tolerance	59s
Map with Custom SerDes	1m 0s
Map with Min Successful	1m 6s
Parallel with Failure Tolerance	57s
Parallel with Max Concurrency	53s
Map with Batch SerDes	56s
Parallel with Batch SerDes	1m 0s
Parallel with Custom SerDes	58s
	26m 11s

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