Use sqlglot to properly check SQL delta files (#19224)

Rather than using dodgy regexes which keep breaking.

Also fixes a regression where it looks like we didn't fail CI if the
delta was in the wrong place.

Author: erikjohnston

.github/workflows/tests.yml

@@ -110,7 +110,7 @@ jobs:
       - uses: actions/setup-python@e797f83bcb11b83ae66e0230d6156d7c80228e7c # v6.0.0
         with:
           python-version: "3.x"
-      - run: "pip install 'click==8.1.1' 'GitPython>=3.1.20'"
+      - run: "pip install 'click==8.1.1' 'GitPython>=3.1.20' 'sqlglot>=28.0.0'"
       - run: scripts-dev/check_schema_delta.py --force-colors
 
   check-lockfile:

changelog.d/19224.misc

@@ -0,0 +1 @@
+Improve robustness of the SQL schema linting in CI.

poetry.lock

@@ -370,6 +370,9 @@ towncrier = ">=18.6.0rc1"
 # Used for checking the Poetry lockfile
 tomli = ">=1.2.3"
 
+# Used for checking the schema delta files
+sqlglot = ">=28.0.0"
+
 
 [build-system]
 # The upper bounds here are defensive, intended to prevent situations like