GitHub Actions: ensure Ubuntu builds are made with the chosen SSL library

The configure parameter was appended to the stage name but not to the
actual command. Fix this.

Cc: Arne Schwabe <arne@rfc2549.org>
Signed-off-by: Antonio Quartulli <a@unstable.cc>
Acked-by: Gert Doering <gert@greenie.muc.de>
Message-Id: <20220114122538.24662-1-a@unstable.cc>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg23539.html
Signed-off-by: Gert Doering <gert@greenie.muc.de>

.github/workflows/build.yaml

@@ -131,7 +131,7 @@ jobs:
       fail-fast: false
       matrix:
         os: [ubuntu-18.04, ubuntu-20.04]
-        sslpkg: [libssl-dev]
+        sslpkg: [libmbedtls-dev]
         ssllib: [mbedtls]
         libname: [mbed TLS]
 
@@ -161,8 +161,8 @@ jobs:
         uses: actions/checkout@v2
       - name: autoconf
         run: autoreconf -fvi
-      - name: configure --with-crypto-library=${{matrix.ssllib}}
-        run: ./configure
+      - name: configure
+        run: ./configure --with-crypto-library=${{matrix.ssllib}}
       - name: make all
         run: make -j3
       - name: make check