Update .travis.yml, .gitlab-ci.yml, flatpak/org.eu.encom.spectral.yaml, .ci/bintray-release.json files

Deleted flatpak/org.eu.encom.matrique.yaml

flatpak/org.eu.encom.matrique.yaml

@@ -1,20 +0,0 @@
-id: org.eu.encom.matrique
-runtime: org.kde.Platform
-runtime-version: 5.11
-sdk: org.kde.Sdk
-command: matrique
-finish-args:
-- --share=ipc
-- --share=network
-- --socket=x11
-- --socket=wayland
-- --device=dri
-- --filesystem=home
-- --talk-name=org.freedesktop.Notifications
-- --talk-name=org.kde.StatusNotifierWatcher
-modules:
-- name: matrique
-  buildsystem: qmake
-  sources:
-  - type: dir
-    path: ../