[mod] ./manage docker.buildx make variables local

The environment variables ..

- SEARX_GIT_VERSION
- VERSION_GITCOMMIT
- SEARX_PYTHON_VERSION
- GITHUB_USER
- SEARX_IMAGE_NAME
- BUILD

are local to the docker.buildx() function, other variables like GIT_URL are
comming from the utils/brand.env file (rebuild by: make buildenv).

Signed-off-by: Markus Heiser <markus.heiser@darmarit.de>

manage

@@ -177,6 +177,13 @@ docker.buildx() {
 docker.build() {
     pyenv.install
 
+    local SEARX_GIT_VERSION
+    local VERSION_GITCOMMIT
+    local SEARX_PYTHON_VERSION
+    local GITHUB_USER
+    local SEARX_IMAGE_NAME
+    local BUILD
+
     build_msg DOCKER build
     # run installation in a subprocess and activate pyenv