build: fix lint error in slider

Fix lint error in slider by running `yarn buildifier
src/material/slider/BUILD.bazel`

Author: zarend

pkg-externals.bzl

@@ -50,6 +50,11 @@ PKG_EXTERNALS = [
     "rxjs",
     "rxjs/operators",
     "selenium-webdriver",
+
+    # TODO: Remove slider deep dependencies after we remove depencies on MDC's javascript
+    "@material/slider/adapter",
+    "@material/slider/foundation",
+    "@material/slider/types",
 ]
 
 # Configures the externals for all MDC packages.

src/material/slider/BUILD.bazel

@@ -29,10 +29,7 @@ ng_module(
         "//src/material/core",
         "@npm//@angular/forms",
         "@npm//@material/base",
-        "@npm//@material/slider/adapter",
-        "@npm//@material/slider/foundation",
-        "@npm//@material/slider/types",
-
+        "@npm//@material/slider",
     ],
 )