chore(deps): upgrade Wagtail to 7.3.2 to fix security advisories (#222)

Bump Wagtail from 7.2.3 to 7.3.2 to resolve five medium-severity
security advisories related to improper permission handling:

- GHSA-67rv-mg8q-5pf3: copying pages
- GHSA-c4mr-889m-vgf6: viewing page history
- GHSA-c6wj-9vcj-75pj: comparing revisions
- GHSA-p5gm-92h4-6pv6: Documents and Images API restrictions
- GHSA-pwm3-7fv4-g6xx: deleting form submissions

Widen the constraint in main.in to >=7.3.2,<7.4 and recompile the
locked requirements. All tests pass and no new project migrations
are required.

Author: matrixise

requirements/dev.txt

@@ -214,7 +214,7 @@ urllib3==2.7.0
     #   requests
 uv==0.11.15
     # via -r requirements/dev.in
-wagtail==7.2.3
+wagtail==7.3.2
     # via
     #   -c requirements/main.txt
     #   wagtail-factories

requirements/main.in

@@ -21,5 +21,5 @@ python-dateutil
 pytz
 redis
 requests>=2.32.5
-wagtail>=7.2,<7.3
+wagtail>=7.3.2,<7.4
 whitenoise

requirements/main.txt

@@ -181,7 +181,7 @@ urllib3==2.7.0
     # via
     #   botocore
     #   requests
-wagtail==7.2.3
+wagtail==7.3.2
     # via -r requirements/main.in
 whitenoise==6.12.0
     # via -r requirements/main.in