fix: upgrade spreadsheet_architect to remove hard axlsx dependency

spreadsheet_architect already pulls-in a newer version of axlsx that
does not have the security vulnerability[1] in it. Ideally we should keep
an eye on the imminent release[2] of spreadsheet_architect that moves
away from axlsx in favour of the community-maintained caxlsx[3].

[1]: randym/axlsx#536
[2]: westonganger/spreadsheet_architect#28 (comment)
[3]: westonganger/spreadsheet_architect@3a6f02d#diff-4ac32a78649ca5bdd8e0ba38b7006a1e

Gemfile

@@ -72,8 +72,6 @@ gem 'bluecloth'
 
 # ODS
 gem 'spreadsheet_architect', '~> 3.2'
-gem 'axlsx', git: 'https://github.com/NoRedInk/axlsx.git',
-             ref: '1a4a6387bf398e2782933ee6607e5589cd15bee3' # 2.1.0-pre-with-new-rubyzip, see https://github.com/randym/axlsx/issues/536
 
 group :development, :test do
   gem 'govuk-lint', '~> 3.10'

Gemfile.lock

@@ -1,13 +1,3 @@
-GIT
-  remote: https://github.com/NoRedInk/axlsx.git
-  revision: 1a4a6387bf398e2782933ee6607e5589cd15bee3
-  ref: 1a4a6387bf398e2782933ee6607e5589cd15bee3
-  specs:
-    axlsx (2.1.0.pre)
-      htmlentities (~> 4.3.1)
-      nokogiri (>= 1.4.1)
-      rubyzip (~> 1.2.1)
-
 GIT
   remote: https://github.com/mailtop/email_validator.git
   revision: 83fe71a4731b0a01e84d1221264cc9802196820e
@@ -76,6 +66,11 @@ GEM
     ast (2.4.0)
     autoprefixer-rails (9.5.1.1)
       execjs
+    axlsx (3.0.0.pre)
+      htmlentities (~> 4.3, >= 4.3.4)
+      mimemagic (~> 0.3)
+      nokogiri (~> 1.8, >= 1.8.2)
+      rubyzip (~> 1.2, >= 1.2.1)
     axlsx_styler (0.2.0)
       activesupport (>= 3.1)
       axlsx (>= 2.0, < 4)
@@ -421,7 +416,6 @@ PLATFORMS
 DEPENDENCIES
   activerecord-import
   autoprefixer-rails
-  axlsx!
   bluecloth
   canonical-rails
   capybara