Ruby 2.7 support, build. Closes #41 (#48)

Removes anon block parameter.

Author: nateberkopec

.github/workflows/build.yml

@@ -14,6 +14,8 @@ jobs:
             bundler_version: 2.4.4
           - ruby: 3.0
             bundler_version: 2.4.4
+          - ruby: 2.7
+            bundler_version: 2.4.4
     env:
       CI: 1
       BUNDLER_VERSION: ${{ matrix.bundler_version }}

.rubocop.yml

@@ -0,0 +1,2 @@
+AllCops:
+  TargetRubyVersion: 2.7

.standard.yml

@@ -1,2 +1,4 @@
 fix: true
 format: progress
+extend_config:
+  - .rubocop.yml

lib/singed/kernel_ext.rb

@@ -1,7 +1,7 @@
 module Kernel
-  def flamegraph(label = nil, open: true, ignore_gc: false, interval: 1000, io: $stdout, &)
+  def flamegraph(label = nil, open: true, ignore_gc: false, interval: 1000, io: $stdout, &block)
     fg = Singed::Flamegraph.new(label: label, ignore_gc: ignore_gc, interval: interval)
-    result = fg.record(&)
+    result = fg.record(&block)
     fg.save
 
     # avoid a dep on a colorizing gem by doing this ourselves