ci: add FreeBSD 14 job, fix issues

- install bash to fix error when running tests:
  ```
  ERROR: test_sshd.test - missing test plan
  ERROR: test_sshd.test - exited with status 127 (command not found?)
  =====================================
  [...]
  # TOTAL: 4
  # PASS:  2
  # SKIP:  0
  # XFAIL: 0
  # FAIL:  0
  # XPASS: 0
  # ERROR: 2
  [...]
  env: bash: No such file or directory
  ```
  Ref: https://github.com/libssh2/libssh2/actions/runs/7133852508/job/19427420687#step:3:3998

- fix sshd issue when running tests:
  ```
    # sshd log:
    #  Server listening on :: port 4711.
    #  Server listening on 0.0.0.0 port 4711.
    #  Authentication refused: bad ownership or modes for file /home/runner/work/libssh2/libssh2/tests/key_rsa.pub
    #  Authentication refused: bad ownership or modes for file /home/runner/work/libssh2/libssh2/tests/openssh_server/authorized_keys
  ```
  Ref: https://github.com/libssh2/libssh2/actions/runs/7134629175/job/19429828342#step:3:4059

Cherry-picked from #1277
Closes #1277

.github/workflows/ci.yml

@@ -558,6 +558,26 @@ jobs:
             make -j3
             make check VERBOSE=1
 
+  build_freebsd_new:
+    name: 'FreeBSD 14 (autotools, openssl, clang, amd64)'
+    runs-on: ubuntu-22.04
+    timeout-minutes: 30
+    steps:
+      - uses: actions/checkout@v4
+      - name: 'autotools'
+        uses: vmactions/freebsd-vm@v1
+        with:
+          # https://ports.freebsd.org/
+          prepare: pkg install -y autoconf automake libtool bash
+          run: |
+            setenv CC clang
+            autoreconf -fi
+            mkdir bld && cd bld && ../configure --enable-werror --enable-debug \
+              --with-crypto=openssl \
+              --disable-docker-tests
+            make -j3
+            make check VERBOSE=1
+
   build_netbsd:
     name: 'NetBSD (cmake, openssl, clang, amd64)'
     runs-on: macos-12