support only the go1.19 and go1.20 (#56)

Go itself only provides suppport for the latest two versions. This
library is going to match that to focus on just Go 1.19 and Go 1.20.
When Go1.21.0 is released this fall we will drop support for Go1.19,
etc.

This really just updates the documentation and the versions we tests
against in CI.

.github/workflows/validate.yaml

@@ -20,7 +20,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        go: [ '1.17', '1.18', '1.19', '1.20']
+        go: ["1.19", "1.20"]
     steps:
       - uses: actions/checkout@v3
       - uses: extractions/setup-just@v1
@@ -55,4 +55,4 @@ jobs:
           CSRX_IMAGE: ghcr.io/nemith/netconf_dut_juniper_csrx:20.3R1.8
           CEOS_IMAGE: ghcr.io/nemith/netconf_dut_arista_ceos64-lab:4.28.3M
           CONFD_IMAGE: ghcr.io/nemith/netconf_dut_tailf_confd:7.8.3
-        run: just inttest/${{ matrix.target }}
+        run: just inttest/${{ matrix.target }}

README.md

@@ -1,6 +1,6 @@
 # Go `netconf` client library
 
-WARNING: This is currently pre-alpha quality.  The API isn't solid yet and a lot of testing still needs to be done as well as additional feaures.
+WARNING: This is currently alpha quality.  The API isn't solid yet and a lot of testing still needs to be done as well as additional feaures.  Working for a solid beta API is incoming.
 
 [![Go Reference](https://pkg.go.dev/badge/github.com/nemith/netconf.svg)](https://pkg.go.dev/github.com/nemith/netconf)
 [![Report Card](https://goreportcard.com/badge/github.com/nemith/netconf)](https://goreportcard.com/report/github.com/nemith/netconf)
@@ -10,7 +10,10 @@ WARNING: This is currently pre-alpha quality.  The API isn't solid yet and a lot
 
 This library is used to create client applications for connecting to network devices via NETCONF.
 
-## Support
+Like Go itself, only the latest two Go versions are tested and supported (Go 1.19 or Go 1.20).
+
+
+## RFC Support
 
 | RFC                                                                               | Support                      |
 | --------------------------------------------------------------------------------- | ---------------------------- |
@@ -38,6 +41,8 @@ There are other RFC around YANG integration that will be looked at later.
 
 See [TODO.md](TODO.md) for a list of what is left to implement these features.
 
+## Comparison
+
 ### Differences from [`github.com/juniper/go-netconf/netconf`](https://pkg.go.dev/github.com/Juniper/go-netconf)
 
 * **Much cleaner, idomatic API, less dumb** I, @nemith, was the original creator of the netconf package and it was my very first Go project and it shows.  There are number of questionable API design, code, and a lot of odd un tested bugs.  Really this rewrite was created to fix this.

go.mod

@@ -1,6 +1,6 @@
 module github.com/nemith/netconf
 
-go 1.18
+go 1.19
 
 require (
 	github.com/stretchr/testify v1.8.4