Updated supported Ruby versions to 3.0, 3.1 and 3.2 (#36)

* Updated supported Ruby versions to 3.0, 3.1 and 3.2

Removed Ruby 2.7 (EOL)

* `minitest 5.19` and above requires `minitest/unit` (fixes #37)

.github/workflows/build.yml

@@ -20,7 +20,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        ruby-version: ['2.7', '3.0', '3.1']
+        ruby-version: ['3.0', '3.1', '3.2']
 
     steps:
       - uses: actions/checkout@v3

README.md

@@ -12,7 +12,7 @@ This gem is the simplest thing that could possibly work that
 reads the output of [exiftool](http://www.sno.phy.queensu.ca/~phil/exiftool)
 and renders it into a ruby hash, with _correctly typed values_ and symbolized keys.
 
-Ruby 2.7 through 3.1 are supported.
+Ruby 3.0 through 3.2 are supported.
 
 ## Ruby Support Deprecation Notice
 
@@ -22,6 +22,7 @@ Ruby Versions due to their [End Of Life](https://www.ruby-lang.org/en/downloads/
 - Ruby 2.4 (EOL 2020-03-31)
 - Ruby 2.5 (EOL 2021-03-31)
 - Ruby 2.6 (EOL 2022-04-12)
+- Ruby 2.7 (EOL 2023-03-31)
 
 The latest Exiftool is recommended, but you'll get that automatically by using the
 [exiftool_vendored](https://github.com/exiftool-rb/exiftool_vendored.rb) gem!

test/test_helper.rb

@@ -6,6 +6,7 @@
 end
 
 require 'minitest/autorun'
+require 'minitest/unit'
 require 'minitest/great_expectations'
 require 'yaml'
 require 'exiftool'