ci(bsd): openbsd 7.4 -> 7.6

Signed-off-by: Christina Sørensen <christina@cafkafk.com>

.github/workflows/unit-tests-bsd.yml

@@ -84,7 +84,7 @@ jobs:
       - name: Compile
         uses: vmactions/openbsd-vm@v1
         with:
-          release: '7.4'
+          release: '7.6'
           usesh: true
           prepare: |
             pkg_add rust rust-rustfmt rust-clippy git