Delete bower.json (#2372)

Bower is deprecated about three years ago and this [triggers `bower install` on Netlify builds](https://docs.netlify.com/configure-builds/manage-dependencies/#bower), which take about a minute.

bower.json

@@ -1,36 +0,0 @@
-{
-  "name": "katex",
-  "main": [
-    "dist/katex.js",
-    "dist/katex.css"
-  ],
-  "homepage": "https://katex.org/",
-  "description": "Fast math typesetting for the web.",
-  "moduleType": [
-    "amd",
-    "globals",
-    "node"
-  ],
-  "license": "MIT",
-  "repository": {
-    "type": "git",
-    "url": "git://github.com/KaTeX/KaTeX.git"
-  },
-  "ignore": [
-    "**/.*",
-    "/*.js",
-    "/*.json",
-    "/*.md",
-    "!/README.md",
-    "/*.sh",
-    "/package.json",
-    "/Makefile",
-    "/test",
-    "/src",
-    "/contrib",
-    "/dockers",
-    "/submodules",
-    "/static",
-    "/website"
-  ]
-}