chore: downgrade minimum Go version in go.mod (caddyserver#6318)

* chore: downgrade minimum Go version in go.mod

* Upgrade certmagic and zerossl

---------

Co-authored-by: Matthew Holt <mholt@users.noreply.github.com>

go.mod

@@ -1,14 +1,16 @@
 module github.com/caddyserver/caddy/v2
 
-go 1.22.3
+go 1.21.0
+
+toolchain go1.22.2
 
 require (
 	github.com/BurntSushi/toml v1.3.2
 	github.com/Masterminds/sprig/v3 v3.2.3
 	github.com/alecthomas/chroma/v2 v2.13.0
 	github.com/aryann/difflib v0.0.0-20210328193216-ff5ff6dc229b
-	github.com/caddyserver/certmagic v0.21.0
-	github.com/caddyserver/zerossl v0.1.2
+	github.com/caddyserver/certmagic v0.21.1
+	github.com/caddyserver/zerossl v0.1.3
 	github.com/dustin/go-humanize v1.0.1
 	github.com/go-chi/chi/v5 v5.0.12
 	github.com/google/cel-go v0.20.0

go.sum

@@ -68,10 +68,10 @@ github.com/aws/smithy-go v1.19.0 h1:KWFKQV80DpP3vJrrA9sVAHQ5gc2z8i4EzrLhLlWXcBM=
 github.com/aws/smithy-go v1.19.0/go.mod h1:NukqUGpCZIILqqiV0NIjeFh24kd/FAa4beRb6nbIUPE=
 github.com/beorn7/perks v1.0.1 h1:VlbKKnNfV8bJzeqoa4cOKqO6bYr3WgKZxO8Z16+hsOM=
 github.com/beorn7/perks v1.0.1/go.mod h1:G2ZrVWU2WbWT9wwq4/hrbKbnv/1ERSJQ0ibhJ6rlkpw=
-github.com/caddyserver/certmagic v0.21.0 h1:yDoifClc4hIxhHer3AxUj4buhF+NzRR6torw/AOnuUE=
-github.com/caddyserver/certmagic v0.21.0/go.mod h1:OgUZNXYV/ylYoFJNmoYVR5nntydLNMQISePPgqZTyhc=
-github.com/caddyserver/zerossl v0.1.2 h1:tlEu1VzWGoqcCpivs9liKAKhfpJWYJkHEMmlxRbVAxE=
-github.com/caddyserver/zerossl v0.1.2/go.mod h1:wtiJEHbdvunr40ZzhXlnIkOB8Xj4eKtBKizCcZitJiQ=
+github.com/caddyserver/certmagic v0.21.1 h1:fVGjStwo05ainOKXymxyKnLsNpm+QZk4DNMzxjN2L14=
+github.com/caddyserver/certmagic v0.21.1/go.mod h1:Zq6pklO9nVRl3DIFUw9gVUfXKdpc/0qwTUAQMBlfgtI=
+github.com/caddyserver/zerossl v0.1.3 h1:onS+pxp3M8HnHpN5MMbOMyNjmTheJyWRaZYwn+YTAyA=
+github.com/caddyserver/zerossl v0.1.3/go.mod h1:CxA0acn7oEGO6//4rtrRjYgEoa4MFw/XofZnrYwGqG4=
 github.com/cenkalti/backoff/v4 v4.2.1 h1:y4OZtCnogmCPw98Zjyt5a6+QwPLGkiQsYW5oUqylYbM=
 github.com/cenkalti/backoff/v4 v4.2.1/go.mod h1:Y3VNntkOUPxTVeUxJ/G5vcM//AlwfmyYozVcomhLiZE=
 github.com/cespare/xxhash v1.1.0 h1:a6HrQnmkObjyL+Gs60czilIUGqrzKutQD6XZog3p+ko=