Bump the govuk template to 0.17.3

# 0.17.3

- Fix colour of H2 headings in footer

# 0.17.2

- Fix a bug with the skip-to-content link and iOS Voiceover
- Migrate @Viewport statement from govuk_frontend_toolkit

# 0.17.1

- Reduce file size of template: removes HTML comments, `type`
attributes on
  scripts, and uses HTML5 charset declaration. alphagov#208
- Switch external link media query to be mobile first alphagov#205
- Sass file cleanups
  - Replace old grid mixins with newer grid from frontend toolkit alphagov#134
  - Remove duplicate grey variables alphagov#201

package.json

@@ -22,8 +22,8 @@
     "express-writer": "0.0.4",
     "govuk-elements-sass": "alphagov/govuk_elements#v1.1.1",
     "govuk_frontend_toolkit": "^4.10.0",
-    "govuk_template_mustache": "^0.17.0",
-    "govuk_template_jinja": "https://github.com/alphagov/govuk_template/releases/download/v0.17.0/jinja_govuk_template-0.17.0.tgz",
+    "govuk_template_mustache": "^0.17.3",
+    "govuk_template_jinja": "https://github.com/alphagov/govuk_template/releases/download/v0.17.3/jinja_govuk_template-0.17.3.tgz",
     "grunt": "0.4.5",
     "grunt-cli": "0.1.13",
     "grunt-concurrent": "0.4.3",