cmake: limit CPack generator to TGZ

To avoid building NSIS packages, which seems not super useful,
and breaks without NSIS (as seen in CI).

Do what curl does and restrict CPack to TGZ.

Follow-up to 04ecdb22fe #1972

Closes #1996

.github/workflows/ci.yml

@@ -979,9 +979,6 @@ jobs:
           else
             system='Windows'
           fi
-          if [[ "${MATRIX_IMAGE}" = *'windows-2025'* ]]; then
-            options+=' -DCPACK_GENERATOR=TGZ'
-          fi
           [ "${MATRIX_CRYPTO}" = 'WinCNG' ] && options+=" -DENABLE_ECDSA_WINCNG=${MATRIX_WINCND_ECDSA}"
           cmake -B bld ${options} \
             -DCMAKE_SYSTEM_NAME="${system}" \

CMakeLists.txt

@@ -584,4 +584,5 @@ set(CPACK_PACKAGE_VERSION_MAJOR ${LIBSSH2_VERSION_MAJOR})
 set(CPACK_PACKAGE_VERSION_MINOR ${LIBSSH2_VERSION_MINOR})
 set(CPACK_PACKAGE_VERSION_PATCH ${LIBSSH2_VERSION_PATCH})
 set(CPACK_PACKAGE_VERSION ${LIBSSH2_VERSION})
+set(CPACK_GENERATOR "TGZ")
 include(CPack)