go: move to 1.27 (toolchain 1.27.1)

go.mod and the Dockerfile builder go from 1.25 to 1.27. The toolchain line
pins 1.27.1 so the server's auto download grabs the patch release, not 1.27.0.
tidy also moved chehsunliu/poker into the direct requires, where it belonged.

go.mod

@@ -1,11 +1,14 @@
 module pete
 
-go 1.25.0
+go 1.27.0
+
+toolchain go1.27.1
 
 require (
 	github.com/BurntSushi/toml v1.6.0
 	github.com/PuerkitoBio/goquery v1.12.0
 	github.com/SherClockHolmes/webpush-go v1.4.0
+	github.com/chehsunliu/poker v0.1.0
 	github.com/coreos/go-oidc/v3 v3.19.0
 	github.com/mmcdole/gofeed v1.3.0
 	go.mau.fi/util v0.9.9
@@ -18,7 +21,6 @@ require (
 require (
 	filippo.io/edwards25519 v1.2.0 // indirect
 	github.com/andybalholm/cascadia v1.3.3 // indirect
-	github.com/chehsunliu/poker v0.1.0 // indirect
 	github.com/dustin/go-humanize v1.0.1 // indirect
 	github.com/go-jose/go-jose/v4 v4.1.4 // indirect
 	github.com/golang-jwt/jwt/v5 v5.2.1 // indirect