Remove Travis as a build system (#552)

Signed-off-by: Kai Kreuzer <kai@openhab.org>

.travis.yml

@@ -1,45 +0,0 @@
-os: linux
-dist: focal
-
-language: java
-jdk: openjdk11
-
-cache:
-  directories:
-  - $HOME/.m2
-  - bundles/org.openhab.ui.basic/npm_cache
-  - bundles/org.openhab.ui.homebuilder/npm_cache
-
-before_install:
-  - echo "MAVEN_OPTS='-Xms1g -Xmx2g'" > ~/.mavenrc
-install:
-  - |
-    function prevent_timeout() {
-        local i=0
-        while [ -e /proc/$1 ]; do
-            # print zero width char every 3 minutes while building
-            if [ "$i" -eq "180" ]; then printf %b '\u200b'; i=0; else i=$((i+1)); fi
-            sleep 1
-        done
-    }
-    function print_reactor_summary() {
-        sed -ne '/\[INFO\] Reactor Summary.*:/,$ p' "$1" | sed 's/\[INFO\] //'
-    }
-    function mvnp() {
-        set -o pipefail # exit build with error when pipes fail
-        local command=(mvn $@)
-        exec "${command[@]}" 2>&1 | # execute, redirect stderr to stdout
-            tee .build.log | # write output to log
-            stdbuf -oL grep -aE '^\[INFO\] Building .+ \[.+\]$' | # filter progress
-            sed -uE 's/^\[INFO\] Building (.*[^ ])[ ]+\[([0-9]+\/[0-9]+)\]$/\2| \1/' | # prefix project name with progress
-            sed -e :a -e 's/^.\{1,4\}|/ &/;ta' & # right align progress with padding
-        local pid=$!
-        prevent_timeout $pid &
-        wait $pid
-    }
-after_success:
-  - print_reactor_summary .build.log
-after_failure:
-  - tail -n 2000 .build.log
-script:
-  - mvnp clean verify -B