Add release workflow.

[HenrikSpiegel]

No description provided.

[codecov-commenter]

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[github-actions]

Code coverage

Name	Coverage (%)
chefStats	77.51
R/across_strata_across_trt.R	38.33
R/barnard_test.R	90.91
R/BreslowDayFunction.R	97.37
R/by_strata_across_trt.R	97.14
R/by_strata_by_trt.R	90.59
R/fisher_vs_barnard.R	100.00
R/hedges_g_.R	0.00
R/odds_ratio_amnog.R	92.31
R/relative_risk.R	100.00
R/risk_diff.R	100.00
R/two_by_two_x.R	76.92
R/use_chefStats.R	0.00
R/utils.R	0.00
R/validate_breslow_day.R	82.35