[core] Fix the CI fail

[oliviertassinari]

The problem:

[mui-pr-bot]

Details of bundle changes.

Comparing: d2fea7f...aef5cc6

bundle	parsed diff	gzip diff	prev parsed	current parsed	prev gzip	current gzip
@material-ui/core	+0.03% 🔺	-0.08%	311,040	311,139	84,131	84,063
@material-ui/core/Paper	0.00%	0.00%	67,277	67,277	19,963	19,963
@material-ui/core/Paper.esm	0.00%	0.00%	60,640	60,640	18,881	18,881
@material-ui/core/Popper	0.00%	0.00%	34,907	34,907	11,808	11,808
@material-ui/core/Textarea	0.00%	0.00%	5,327	5,327	2,290	2,290
@material-ui/core/styles/createMuiTheme	0.00%	0.00%	15,898	15,898	5,771	5,771
@material-ui/core/useMediaQuery	0.00%	0.00%	2,106	2,106	974	974
@material-ui/lab	+0.04% 🔺	-0.08%	141,666	141,722	42,804	42,769
@material-ui/styles	0.00%	0.00%	50,833	50,833	15,014	15,014
@material-ui/system	0.00%	0.00%	11,765	11,765	3,926	3,926
Button	0.00%	0.00%	85,621	85,621	25,586	25,586
Modal	0.00%	0.00%	79,229	79,229	23,924	23,924
colorManipulator	0.00%	0.00%	3,904	3,904	1,543	1,543
docs.landing	0.00%	0.00%	50,908	50,908	11,210	11,210
docs.main	+0.01% 🔺	0.00%	647,152	647,205	201,827	201,836
packages/material-ui/build/umd/material-ui.production.min.js	+0.02% 🔺	+0.06% 🔺	292,541	292,609	82,141	82,190

Generated by 🚫 dangerJS against aef5cc6