Internal/add gh actions and tests (#3)

* add gh actions and templates
* add show-versions in Makefile
* force go 1.20
* added test facilities

.github/ISSUE_TEMPLATE/bug_report.md

@@ -0,0 +1,31 @@
+---
+name: Bug report
+about: Create a report to help us improve
+title: "[bug-report]"
+labels: bug
+assignees: TLINDEN
+
+---
+
+**Describtion**
+<!-- Please provide a clear and concise description of the issue: -->
+
+
+**Steps To Reproduce**
+<!-- Please detail the steps to reproduce the behavior: -->
+
+
+**Expected behavior**
+<!-- What do you expected to happen instead? -->
+
+
+**Version information**
+<!--
+Please provide as much version information as possible:
+- if you have just installed a binary, provide the output of: rpn -v
+- if you installed from source, provide the output of: make show-version
+- provide additional details: operating system and version and shell environment
+-->
+
+
+**Additional informations**

.github/ISSUE_TEMPLATE/feature_request.md

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+---
+name: Feature request
+about: Suggest a feature
+title: "[feature-request]"
+labels: feature-request
+assignees: TLINDEN
+
+---
+
+**Describtion**
+<!-- Please provide a clear and concise description of the feature you desire: -->
+
+
+
+**Version information**
+<!--
+Just in case the feature is already present, please provide as
+much version information as possible:
+- if you have just installed a binary, provide the output of: rpn -v
+- if you installed from source, provide the output of: make show-version
+- provide additional details: operating system and version and shell environment
+-->
+

.github/workflows/ci.yaml

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+name: build-and-test-rpn
+on: [push, pull_request]
+jobs:
+  build:
+    strategy:
+      matrix:
+        version: [1.21]
+        os: [ubuntu-latest, windows-latest, macos-latest]
+    name: Build
+    runs-on: ${{ matrix.os }}
+    steps:
+    - name: Set up Go
+      uses: actions/setup-go@v3
+      with:
+        go-version: ${{ matrix.version }}
+      id: go
+
+    - name: checkout
+      uses: actions/checkout@v3
+
+    - name: build
+      run: go build
+
+    - name: test
+      run: make test
+
+  golangci:
+    name: lint
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/setup-go@v3
+        with:
+          go-version: 1.21
+      - uses: actions/checkout@v3
+      - name: golangci-lint
+        uses: golangci/golangci-lint-action@v3