gitlab-ci: replace 'linux' tags with 'linux-x86_64' in upload jobs

These were missed by commit 94d82d91d5 (gitlab-ci: replace 'linux'
tags with 'linux-x86_64', 2022-11-30).

.gitlab/upload.yml

@@ -6,7 +6,7 @@
     tags:
         - cmake
         - docker
-        - linux
+        - linux-x86_64
         - build
     environment:
         name: rsync-upload
@@ -25,7 +25,7 @@
     tags:
         - cmake
         - docker
-        - linux
+        - linux-x86_64
         - build
     environment:
         name: rsync-upload