use terser rather than uglifier

Uglifier(harmony: true) fails; :uglifier does not suit for ES6

See: lautis/uglifier#185

Gemfile.lock

@@ -216,8 +216,8 @@ GEM
       kaminari-core (= 1.2.2)
     kaminari-core (1.2.2)
     language_server-protocol (3.17.0.3)
-    libdatadog (3.0.0.1.0-x86_64-linux)
-    libddwaf (1.9.0.0.1-x86_64-linux)
+    libdatadog (3.0.0.1.0)
+    libddwaf (1.9.0.0.1)
       ffi (~> 1.0)
     lograge (0.13.0)
       actionpack (>= 4)
@@ -247,6 +247,7 @@ GEM
     mime-types-data (3.2023.0218.1)
     mini_magick (4.12.0)
     mini_mime (1.1.2)
+    mini_portile2 (2.8.4)
     minitest (5.19.0)
     mixpanel-ruby (2.3.0)
     momentjs-rails (2.29.4.1)
@@ -276,7 +277,8 @@ GEM
     nexmo-jwt (0.1.2)
       jwt (~> 2)
     nio4r (2.5.9)
-    nokogiri (1.15.3-x86_64-linux)
+    nokogiri (1.15.3)
+      mini_portile2 (~> 2.8.2)
       racc (~> 1.4)
     optimist (3.1.0)
     parallel (1.23.0)