Add Gitea Actions - Githubissues

Details:

Ci name: Gitea Actions
Website: [e.g. https://travis-ci.com/]
Default env variables: Most (possibly all) from GitHub actions, plus GITEA_ACTIONS, and for the act runner ACT

Environment variables

Environment variables example

``` GITHUB_TOKEN=*** GITHUB_STATE=/var/run/act/workflow/statecmd.txt ACTIONS_RUNTIME_TOKEN=*** ACTIONS_CACHE_URL= CI=true HOSTNAME= GITHUB_ENV=/var/run/act/workflow/envs.txt SHLVL=1 HOME=/root RUNNER_TEMP=/tmp GITHUB_EVENT_PATH=/var/run/act/workflow/event.json GITHUB_REPOSITORY_OWNER= ACT=true GITHUB_RETENTION_DAYS= GITHUB_HEAD_REF= GITHUB_GRAPHQL_URL= RUNNER_OS=Linux GITHUB_API_URL= ACTIONS_RUNTIME_URL= GITEA_ACTIONS=true GITHUB_WORKFLOW= GITHUB_RUN_ID=120 ImageOS=ubuntu20 GITHUB_REF_TYPE= GITHUB_BASE_REF= GITHUB_ACTION_REPOSITORY= PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin RUNNER_TOOL_CACHE=/opt/hostedtoolcache RUNNER_TRACKING_ID= GITEA_ACTIONS_RUNNER_VERSION=v0.2.3 RUNNER_ARCH=X64 GITHUB_ACTION=0 JOB_CONTAINER_NAME= GITHUB_RUN_NUMBER= LANG=C.UTF-8 GITHUB_REPOSITORY= GITHUB_REF_NAME= GITHUB_ACTION_REF= GITHUB_ACTIONS=true GITHUB_ACTION_PATH= GITHUB_WORKSPACE=/root/.cache/act// GITHUB_JOB= RUNNER_PERFLOG=/dev/null GITHUB_SHA= GITHUB_REF= GITHUB_ACTOR= GITHUB_PATH=/var/run/act/workflow/pathcmd.txt PWD=/root/.cache/act// GITHUB_EVENT_NAME=push GITHUB_SERVER_URL= GITHUB_OUTPUT=/var/run/act/workflow/outputcmd.txt GITHUB_STEP_SUMMARY=/var/run/act/workflow/SUMMARY.md ```

Additional context

Given how much this is designed to mimic GitHub Actions I'm not sure how reasonable/viable this is, but it was causing me some issues so I thought I'd flag it.

watson / ci-info

Add Gitea Actions #113