update to OpenBSD 7.5 runner

Author: jiixyj

.github/workflows/build.yml

@@ -66,16 +66,11 @@ jobs:
       id: test
       uses: vmactions/openbsd-vm@v1
       with:
-        release: 7.4
+        release: 7.5
         envs: 'BUILD_TYPE'
         usesh: true
         prepare: pkg_add cmake
         run: |
-          cd /tmp || exit 1
-          ftp https://cloudflare.cdn.openbsd.org/pub/OpenBSD/7.4/amd64/comp74.tgz || exit 1
-          cd / || exit 1
-          tar xzvphf /tmp/comp71.tgz
-          cd || exit 1
           mkdir build || exit 1
           cd build || exit 1
           cmake $GITHUB_WORKSPACE -DCMAKE_BUILD_TYPE=$BUILD_TYPE || exit 1