Replace //tools/base/third_party deps with @maven

Bug: 190268212
Test: presubmit
Change-Id: Ie4c2f38b835dc621814ad180ed735875efaced34
diff --git a/BUILD b/BUILD
index e2f12ac..5322f4d 100644
--- a/BUILD
+++ b/BUILD
@@ -65,7 +65,7 @@
     test_class = "com.android.apksig.AllTests",
     deps = [
         ":apksig-all",
-        "//tools/base/third_party:junit_junit",
+        "@maven//:junit.junit",
     ],
 )