Update Bundler version and update test to avoid hardcoding it

Author: eregon

doc/contributor/updating-ruby.md

@@ -149,7 +149,8 @@ In a separate commit, update all of these:
 * Update `doc/legal/legal.md`
 * Update method lists - see `spec/truffle/methods_spec.rb`
 * Run `jt test gems default-bundled-gems`
-* Grep for the old version with `git grep -F x.y.z`
+* Grep for the old Ruby version with `git grep -F x.y.z`
+* Grep for the old Bundler version with `git grep -F x.y.z`
 * If `tool/id.def` or `lib/cext/include/truffleruby/internal/id.h` has changed, `jt build core-symbols` and check for correctness.
 
 For a new major version:

test/truffle/ecosystem/blog6/Gemfile.lock.renamed

@@ -169,4 +169,4 @@ RUBY VERSION
    ruby 2.4.4p0 (truffleruby 0.0-c3a45cc6)
 
 BUNDLED WITH
-   2.2.22
+   2.2.32

test/truffle/integration/bundler-version.sh

@@ -11,7 +11,7 @@ GEM_HOME=$PWD/temp-gem-home jt ruby -S gem install --local "$gem_test_pack/gem-c
 
 output=$(GEM_HOME=$PWD/temp-gem-home jt ruby -Ctest/truffle/integration/bundler-version/one bundler-version.rb)
 
-if [ "$output" = '"1.17.3"' ]; then
+if [ "$output" = 'true' ]; then
   echo Success
 else
   echo Unexpected bundler 1 output
@@ -21,7 +21,7 @@ fi
 
 output=$(GEM_HOME=$PWD/temp-gem-home jt ruby -Ctest/truffle/integration/bundler-version/two bundler-version.rb)
 
-if [ "$output" = '"2.2.22"' ]; then
+if [ "$output" = 'true' ]; then
   echo Success
 else
   echo Unexpected bundler 2 output

test/truffle/integration/bundler-version/one/bundler-version.rb

@@ -1,2 +1,2 @@
 require 'bundler/setup'
-p Bundler::VERSION
+p Bundler::VERSION == "1.17.3"

test/truffle/integration/bundler-version/two/Gemfile.lock

@@ -8,4 +8,4 @@ PLATFORMS
 DEPENDENCIES
 
 BUNDLED WITH
-   2.2.22
+   2.2.32

test/truffle/integration/bundler-version/two/bundler-version.rb

@@ -1,2 +1,7 @@
 require 'bundler/setup'
-p Bundler::VERSION
+
+require 'json'
+versions = File.expand_path('../../../../../versions.json', __dir__)
+expected = JSON.load(File.read(versions)).dig('gems', 'default', 'bundler')
+
+p Bundler::VERSION == expected