ci: test with ArangoDB 3.12

There is a breaking change in ArangoDB 3.12 that the default locale changes
from en_US to en_US_POSIX. cruddl has some logic that relies on the order
of values according to the non-POSIX locale. Therefore, we need to set it
using LOCALE in the tests.

Consider this:

    for a in ["Scal", "PART", "part"] sort a return a

cruddl assumes it to be

    [
      "PART",
      "part",
      "Scal"
    ]

but in 3.12 without locale set (so en_US_POSIX) is used, it would be:

    [
      "PART",
      "Scal",
      "part"
    ]

.github/workflows/ci.yml

@@ -5,7 +5,14 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        arango-image: ['arangodb:3.8', 'arangodb:3.9', 'arangodb:3.10', 'arangodb:3.11']
+        arango-image:
+          [
+            "arangodb:3.8",
+            "arangodb:3.9",
+            "arangodb:3.10",
+            "arangodb:3.11",
+            "arangodb:3.12",
+          ]
         node-version: [14.x, 16.x, 18.x]
     steps:
       - uses: actions/checkout@v2
@@ -14,7 +21,7 @@ jobs:
         with:
           node-version: ${{ matrix.node-version }}
       - run:
-          docker run --name arangodb -p 127.0.0.1:8529:8529 -d -e ARANGO_NO_AUTH=1 ${{
+          docker run --name arangodb -p 127.0.0.1:8529:8529 -d -e ARANGO_NO_AUTH=1 -e LANG=en_US ${{
           matrix.arango-image }}
       - run: timeout 10 docker logs --follow arangodb || true # wait until arangodb is started
       - run: curl -L http://localhost:8529/_api/version

README.md

@@ -136,7 +136,13 @@ When done, stop the instance with `npm run stop_arangodb`
 
 cruddl currently supports the following versions of ArangoDB:
 
-- 3.8
-- 3.9
-- 3.10
-- 3.11
+-   3.8
+-   3.9
+-   3.10
+-   3.11
+-   3.12
+
+Starting with ArangoDB 3.12, the default locale for new databases has been changed from `en_US` to
+`en_US_POSIX`. cruddl does not support `en_US_POSIX` at the moment, so you need to change the locale
+to `en_US`. See
+[the ArangoDB announcemenent](https://docs.arangodb.com/3.12/release-notes/version-3.12/incompatible-changes-in-3-12/#default-server-language-changed).