Bump rubocop

Use old style for Style/PercentLiteralDelimiters for now. Maybe we can
change this in the future, because the ruby style guide suggests to
use `[]`.

See: https://github.com/bbatsov/ruby-style-guide#percent-literal-braces

.rubocop.yml

@@ -189,6 +189,16 @@ Style/EmptyLineBetweenDefs:
 Style/NumericPredicate:
   EnforcedStyle: comparison
 
+# Old defaults from rubocop < 0.48.1 (Maybe change this in the future?)
+Style/PercentLiteralDelimiters:
+  PreferredDelimiters:
+    default: '()'
+    '%i': '()'
+    '%I': '()'
+    '%r': '{}'
+    '%w': '()'
+    '%W': '()'
+
 ### backward compatibility
 
 # only with ruby >= 2.3
@@ -207,8 +217,3 @@ Performance/RegexpMatch:
 Rails/HttpPositionalArguments:
   Exclude:
     - "spec/controllers/diaspora_federation/rails4_spec.rb"
-
-# remove with next rubocop update, see https://github.com/bbatsov/rubocop/issues/4172
-Style/MixinGrouping:
-  Exclude:
-    - "spec/**/*"

Gemfile

@@ -19,7 +19,7 @@ group :development do
   # code style
   gem "pronto",         "0.8.2",  require: false
   gem "pronto-rubocop", "0.8.1",  require: false
-  gem "rubocop",        "0.48.0", require: false
+  gem "rubocop",        "0.48.1", require: false
 
   # automatic test runs
   gem "guard-rspec",   require: false

Gemfile.lock

@@ -182,7 +182,7 @@ GEM
       rspec-mocks (~> 3.5.0)
       rspec-support (~> 3.5.0)
     rspec-support (3.5.0)
-    rubocop (0.48.0)
+    rubocop (0.48.1)
       parser (>= 2.3.3.1, < 3.0)
       powerpack (~> 0.1)
       rainbow (>= 1.99.1, < 3.0)
@@ -253,7 +253,7 @@ DEPENDENCIES
   rspec-collection_matchers (~> 1.1.2)
   rspec-json_expectations (~> 2.1)
   rspec-rails (~> 3.5.1)
-  rubocop (= 0.48.0)
+  rubocop (= 0.48.1)
   simplecov (= 0.13.0)
   simplecov-rcov (= 0.2.3)
   spring