ci: Use extends to define extra libfprint variables

This allows to merge the values when included instead of replacing the whole
variables stanza.

.gitlab-ci/libfprint-templates.yaml

@@ -1,26 +1,26 @@
-variables:
+.libfprint_common_variables:
   LIBFPRINT_DEPENDENCIES:
-      doxygen
-      flatpak-builder
-      gcc
-      gcc-c++
-      gcovr
-      git
-      glib2-devel
-      glibc-devel
-      gobject-introspection-devel
-      gtk-doc
-      gtk3-devel
-      libabigail
-      libgusb-devel
-      libX11-devel
-      libXv-devel
-      meson
-      nss-devel
-      pixman-devel
-      python3-cairo
-      python3-gobject
-      systemd
-      umockdev
-      uncrustify
-      valgrind
+    doxygen
+    flatpak-builder
+    gcc
+    gcc-c++
+    gcovr
+    git
+    glib2-devel
+    glibc-devel
+    gobject-introspection-devel
+    gtk-doc
+    gtk3-devel
+    libabigail
+    libgusb-devel
+    libX11-devel
+    libXv-devel
+    meson
+    nss-devel
+    pixman-devel
+    python3-cairo
+    python3-gobject
+    systemd
+    umockdev
+    uncrustify
+    valgrind