Bump Go version and drop action/setup-go (#9)

Modern Go toolchains (available at the base image) can automatically
install the required version of Go based on the `go.mod` file, so we can
remove the `actions/setup-go` step from the workflow.

We keep the minimum required Go version in the `go.mod` file for broad
compatibility (1.19), but we use a more recent version when interacting
with the code (e.g. `go test` in the existing update.yml workflow).

    go get toolchain@latest

https://go.dev/blog/toolchain#:~:text=Or%20if%20you%20want%20to%20start%20using,toolchain%20version%20using%20the%20GOTOOLCHAIN%20environment%20variable.

.github/workflows/update.yml

@@ -49,12 +49,6 @@ jobs:
         run: |
           RELEASE_DATE="$(awk -f release_date -v RS='\r\n' cedict_1_0_ts_utf-8_mdbg.txt)"
           git commit -m "CC-CEDICT ${RELEASE_DATE}"
-      - uses: "actions/setup-go@v6"
-        if: "fromJSON(steps.diff.outputs.changed)"
-        with:
-          go-version-file: "go.mod"
-          # cache: true
-          # cache-dependency-path: "go.sum"
       - name: "Test"
         if: "fromJSON(steps.diff.outputs.changed)"
         run: "go test -v -count=1"

go.mod

@@ -1,3 +1,5 @@
 module github.com/rhcarvalho/cedict
 
 go 1.19
+
+toolchain go1.26.5