RubyGem "gobject-introspection" が Linux Mint にインストールできない

Linux Mint 19.3 に gem "gtk2" をインストールしようとしてハマりました。

Fetching gobject-introspection 3.4.1
Installing gobject-introspection 3.4.1 with native extensions
Gem::Ext::BuildError: ERROR: Failed to build gem native extension.

current directory:
/home/tomoki/Documents/Ruby265/vendor/bundle/ruby/2.6.0/gems/gobject-introspection-3.4.1/ext/gobject-introspection
/home/tomoki/.rbenv/versions/2.6.5/bin/ruby -I
/home/tomoki/.rbenv/versions/2.6.5/lib/ruby/2.6.0 -r
./siteconf20200306-4424-xngtrx.rb extconf.rb
checking for --enable-debug-build option... no
checking for -Wall option to compiler... yes
checking for -Waggregate-return option to compiler... yes
checking for -Wcast-align option to compiler... yes
checking for -Wextra option to compiler... yes
checking for -Wformat=2 option to compiler... yes
checking for -Winit-self option to compiler... yes
checking for -Wlarger-than-65500 option to compiler... yes
checking for -Wmissing-declarations option to compiler... yes
checking for -Wmissing-format-attribute option to compiler... yes
checking for -Wmissing-include-dirs option to compiler... yes
checking for -Wmissing-noreturn option to compiler... yes
checking for -Wmissing-prototypes option to compiler... yes
checking for -Wnested-externs option to compiler... no
checking for -Wold-style-definition option to compiler... yes
checking for -Wpacked option to compiler... yes
checking for -Wp,-D_FORTIFY_SOURCE=2 option to compiler... yes
checking for -Wpointer-arith option to compiler... yes
checking for -Wundef option to compiler... yes
checking for -Wout-of-line-declaration option to compiler... no
checking for -Wunsafe-loop-optimizations option to compiler... yes
checking for -Wwrite-strings option to compiler... yes
checking for Homebrew... no
checking for gobject-introspection-1.0... no
*** extconf.rb failed ***
Could not create Makefile due to some reason, probably lack of necessary
libraries and/or headers.  Check the mkmf.log file for more details.  You may
need configuration options.

Provided configuration options:
	--with-opt-dir
	--without-opt-dir
	--with-opt-include
	--without-opt-include=${opt-dir}/include
	--with-opt-lib
	--without-opt-lib=${opt-dir}/lib
	--with-make-prog
	--without-make-prog
	--srcdir=.
	--curdir
	--ruby=/home/tomoki/.rbenv/versions/2.6.5/bin/$(RUBY_BASE_NAME)
	--enable-debug-build
	--disable-debug-build
	--with-pkg-config
	--without-pkg-config
	--with-override-variables
	--without-override-variables

To see why this extension failed to compile, please check the mkmf.log which can
be found here:

/home/tomoki/Documents/Ruby265/vendor/bundle/ruby/2.6.0/extensions/x86_64-linux/2.6.0/gobject-introspection-3.4.1/mkmf.log

extconf failed, exit code 1

Gem files will remain installed in
/home/tomoki/Documents/Ruby265/vendor/bundle/ruby/2.6.0/gems/gobject-introspection-3.4.1
for inspection.
Results logged to
/home/tomoki/Documents/Ruby265/vendor/bundle/ruby/2.6.0/extensions/x86_64-linux/2.6.0/gobject-introspection-3.4.1/gem_make.out

An error occurred while installing gobject-introspection (3.4.1), and
Bundler cannot continue.
Make sure that `gem install gobject-introspection -v '3.4.1' --source
'https://rubygems.org/'` succeeds before bundling.

In Gemfile:
  gio2 was resolved to 3.4.1, which depends on
    gobject-introspection

　
パッケージがないのかと思って apt-get install してみましたが、

$ sudo apt-get install -y gobject-introspection
パッケージリストを読み込んでいます... 完了
依存関係ツリーを作成しています                
状態情報を読み取っています... 完了
gobject-introspection はすでに最新バージョン (1.56.1-1) です。

という感じ。
　
正解はここにありました。

$ sudo apt install libgirepository1.0-dev

これで OK。