Internal/add gh actions and tests (#3)

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

Makefile

@@ -39,10 +39,6 @@ ifdef HAVE_POD
 	  echo "var manpage = \`" >> $*.go
 	  pod2text $*.pod >> $*.go
 	  echo "\`" >> $*.go
-
-	  echo "var usage = \`" >> $*.go
-	  awk '/SYNOPS/{f=1;next} /DESCR/{f=0} f' $*.pod  | sed 's/^    //' >> $*.go
-	  echo "\`" >> $*.go
 endif
 
 buildlocal:
@@ -59,7 +55,6 @@ clean:
 
 test:
 	go test -v ./...
-	bash t/test.sh
 
 singletest:
 	@echo "Call like this: ''make singletest TEST=TestPrepareColumns MOD=lib"
@@ -77,3 +72,15 @@ buildall:
 
 release: buildall
 	gh release create v$(VERSION) --generate-notes releases/*
+
+show-versions: buildlocal
+	@echo "### rpn version:"
+	@./rpn -v
+
+	@echo
+	@echo "### go module versions:"
+	@go list -m all
+
+	@echo
+	@echo "### go version used for building:"
+	@grep -m 1 go go.mod