[bug report] math.div sass compilation error

### Element UI version
2.15.6

### OS/Browsers version
mac

### Vue version
2.6.14

### Reproduction Link
https://github.com/ElemeFE/element/pull/21019

### Steps to reproduce
Syntax Error: SassError: Undefined function.
╷
33 │ margin-right: math.div($--tooltip-arrow-size, 2);
│ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
╵
node_modules/_element-ui@2.15.7@element-ui/packages/theme-chalk/src/popper.scss 33:19 @content
node_modules/_element-ui@2.15.7@element-ui/packages/theme-chalk/src/mixins/mixins.scss 83:5 b()
node_modules/_element-ui@2.15.7@element-ui/packages/theme-chalk/src/popper.scss 5:1 @import
node_modules/_element-ui@2.15.7@element-ui/packages/theme-chalk/src/select-dropdown.scss 3:9 @import
node_modules/_element-ui@2.15.7@element-ui/packages/theme-chalk/src/select.scss 4:9 @import
node_modules/_element-ui@2.15.7@element-ui/packages/theme-chalk/src/pagination.scss 4:9 @import
node_modules/_element-ui@2.15.7@element-ui/packages/theme-chalk/src/index.scss 2:9 @import
src/styles/element-variables.scss 1039:9

### What is Expected?
编译正常

### What is actually happening?
Syntax Error: SassError: Undefined function.
╷
33 │ margin-right: math.div($--tooltip-arrow-size, 2);
│ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
╵
node_modules/_element-ui@2.15.7@element-ui/packages/theme-chalk/src/popper.scss 33:19 @content
node_modules/_element-ui@2.15.7@element-ui/packages/theme-chalk/src/mixins/mixins.scss 83:5 b()
node_modules/_element-ui@2.15.7@element-ui/packages/theme-chalk/src/popper.scss 5:1 @import
node_modules/_element-ui@2.15.7@element-ui/packages/theme-chalk/src/select-dropdown.scss 3:9 @import
node_modules/_element-ui@2.15.7@element-ui/packages/theme-chalk/src/select.scss 4:9 @import
node_modules/_element-ui@2.15.7@element-ui/packages/theme-chalk/src/pagination.scss 4:9 @import
node_modules/_element-ui@2.15.7@element-ui/packages/theme-chalk/src/index.scss 2:9 @import
src/styles/element-variables.scss 1039:9