Updated gvcov to vcovG

[mbannick]

Updates all references of gvcov to vcovG. This includes the snapshots for testthat.

[github-actions]

Code Coverage Summary

Filename                     Stmts    Miss  Cover    Missing
-------------------------  -------  ------  -------  --------------------
R/bias.R                        11       0  100.00%
R/find_data.R                    3       0  100.00%
R/predict_couterfactual.R       48       1  97.92%   55
R/prediction_cf.R                3       0  100.00%
R/robin_glm.R                   33       0  100.00%
R/treatment_effect.R           116       3  97.41%   42, 80-81
R/utils.R                       21       0  100.00%
R/variance_anhecova.R           44      19  56.82%   28, 43-44, 57, 63-78
R/variance_hc.R                  9       0  100.00%
TOTAL                          288      23  92.01%

Diff against main

Filename      Stmts    Miss  Cover
----------  -------  ------  --------
TOTAL             0       0  +100.00%

Results for commit: dc3e8b5

Minimum allowed coverage is 80%

♻️ This comment has been updated with latest results

[github-actions]

Unit Tests Summary

 1 files   7 suites   0s ⏱️
25 tests 16 ✅  9 💤 0 ❌
66 runs  56 ✅ 10 💤 0 ❌

Results for commit dc3e8b5.

[github-actions]

Unit Test Performance Difference

Additional test case details

Test Suite	$Status$	Time on main	$±Time$	Test Case
variance	💀	$0.03$	$-0.03$	gvcov_works
variance	👶		$+0.03$	vcovG_works

Results for commit 47698d3

♻️ This comment has been updated with latest results.