[Slider] Remove from the lab

[oliviertassinari]

-import { Slider } from '@material-ui/lab';
+import { Slider } from '@material-ui/core';

[mui-pr-bot]

@material-ui/lab: parsed: -7.53% 😍, gzip: -6.79% 😍

Details of bundle changes.

Comparing: e570b15...7f377f8

bundle	parsed diff	gzip diff	prev parsed	current parsed	prev gzip	current gzip
@material-ui/core	0.00%	-0.02%	332,012	332,012	90,652	90,631
@material-ui/core/Paper	0.00%	+0.01% 🔺	68,710	68,710	20,472	20,474
@material-ui/core/Paper.esm	-0.00%	-0.02%	62,148	62,147	19,220	19,217
@material-ui/core/Popper	0.00%	0.00%	28,397	28,397	10,159	10,159
@material-ui/core/Textarea	0.00%	+0.19% 🔺	5,082	5,082	2,132	2,136
@material-ui/core/TrapFocus	0.00%	0.00%	3,766	3,766	1,596	1,596
@material-ui/core/styles/createMuiTheme	0.00%	0.00%	16,348	16,348	5,818	5,818
@material-ui/core/useMediaQuery	0.00%	0.00%	2,488	2,488	1,050	1,050
@material-ui/lab	-7.53%	-6.79%	154,833	143,172	46,936	43,751
@material-ui/styles	-0.00%	0.00%	51,470	51,469	15,305	15,305
@material-ui/system	0.00%	-0.23%	15,581	15,581	4,351	4,341
Button	-0.00%	+0.04% 🔺	78,683	78,682	24,037	24,047
Modal	0.00%	-0.02%	14,542	14,542	5,114	5,113
Portal	0.00%	0.00%	2,907	2,907	1,318	1,318
Rating	0.00%	-0.03%	70,013	70,013	21,873	21,867
Slider	+0.03% 🔺	+0.07% 🔺	75,134	75,154	23,201	23,217
colorManipulator	0.00%	0.00%	3,835	3,835	1,519	1,519
docs.landing	0.00%	0.00%	54,267	54,267	14,345	14,345
docs.main	0.00%	0.00%	581,958	581,958	186,307	186,307
packages/material-ui/build/umd/material-ui.production.min.js	0.00%	0.00%	302,867	302,867	87,077	87,077

Generated by 🚫 dangerJS against 7f377f8