refactor: remove deprecated package "github.com/pkg/errors"

[sbchaos]

Closes #173

[coveralls]

Pull Request Test Coverage Report for Build 1931921903

• 32 of 126 (25.4%) changed or added relevant lines in 29 files are covered.
• 1 unchanged line in 1 file lost coverage.
• Overall coverage increased (+0.004%) to 72.713%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
ext/datastore/bigquery/table.go	0	1	0.0%
ext/scheduler/airflow2/compiler/compiler.go	1	2	50.0%
job/replay.go	0	1	0.0%
models/datastore.go	0	1	0.0%
models/instance.go	0	1	0.0%
run/jinja_engine.go	0	1	0.0%
utils/file.go	0	1	0.0%
ext/datastore/bigquery/external_table.go	0	2	0.0%
ext/datastore/bigquery/factory.go	0	2	0.0%
ext/datastore/bigquery/standard_view.go	0	2	0.0%

Files with Coverage Reduction	New Missed Lines	%
run/service.go	1	81.98%

Totals
Change from base Build 1929658338:	0.004%
Covered Lines:	5223
Relevant Lines:	7183

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💛 - Coveralls