fix(ci): add "which" until yast2-devtools gets fixed (#1610)

- The `which` command is required by `y2makepot`, from the
`yast2-devtools` package.
- yast/yast-devtools#176 fixes the problem, but
until
the fix lands in Factory, we would like to have our CI working again (it
has been broken for at least two weeks).

.github/workflows/weblate-update-pot.yml

@@ -29,7 +29,7 @@ jobs:
       - name: Install tools
         run: |
           RUBY_VERSION=$(ruby -e "puts RbConfig::CONFIG['ruby_version']")
-          zypper --non-interactive install --no-recommends diffutils git gettext-tools npm-default "rubygem(ruby:$RUBY_VERSION:yast-rake)" "rubygem(ruby:$RUBY_VERSION:gettext)" yast2-devtools
+          zypper --non-interactive install --no-recommends diffutils git gettext-tools npm-default "rubygem(ruby:$RUBY_VERSION:yast-rake)" "rubygem(ruby:$RUBY_VERSION:gettext)" yast2-devtools which
 
       - name: Checkout Agama sources
         uses: actions/checkout@v4