Update dependencies

@babel/core                                  7.7.7  →    7.8.6
 @babel/plugin-proposal-class-properties      7.7.4  →    7.8.3
 @babel/plugin-proposal-decorators            7.7.4  →    7.8.3
 @babel/plugin-proposal-object-rest-spread    7.7.7  →    7.8.3
 @babel/plugin-syntax-class-properties        7.7.4  →    7.8.3
 @babel/plugin-syntax-decorators              7.7.4  →    7.8.3
 @babel/plugin-syntax-dynamic-import          7.7.4  →    7.8.3
 @babel/plugin-syntax-object-rest-spread      7.7.4  →    7.8.3
 @babel/preset-env                            7.7.7  →    7.8.6
 @babel/preset-react                          7.7.4  →    7.8.3
 autoprefixer                                ^9.7.3  →   ^9.7.4
 gulp-imagemin                               ^6.2.0  →   ^7.1.0
 jsonfile                                    ^5.0.0  →   ^6.0.0
 node-sass                                  ^4.13.0  →  ^4.13.1
 semver                                      ^7.1.1  →   ^7.1.3
 svelte                                     ^3.16.7  →  ^3.19.1
 typescript                                   3.7.4  →    3.8.2
 webpack                                    ^4.41.5  →  ^4.41.6
 yargs                                      ^15.0.2  →  ^15.1.0
 mocha                                       ^6.2.2  →   ^7.1.0