Shift to go-toml v2

A benchark building a site with 200 pages with TOML front matter:

```bash
name                                  old time/op    new time/op    delta
SiteNew/Regular_TOML_front_matter-16    48.5ms ± 1%    47.1ms ± 1%  -2.85%  (p=0.029 n=4+4)

name                                  old alloc/op   new alloc/op   delta
SiteNew/Regular_TOML_front_matter-16    16.9MB ± 0%    16.7MB ± 0%  -1.56%  (p=0.029 n=4+4)

name                                  old allocs/op  new allocs/op  delta
SiteNew/Regular_TOML_front_matter-16      302k ± 0%      296k ± 0%  -2.20%  (p=0.029 n=4+4)
```

Note that the front matter unmarshaling is only a small part of building a site, so the above is very good.

Fixes gohugoio#8801

go.mod

@@ -2,7 +2,6 @@ module github.com/gohugoio/hugo
 
 require (
 	github.com/BurntSushi/locker v0.0.0-20171006230638-a6e239ea1c69
-	github.com/BurntSushi/toml v0.3.1
 	github.com/PuerkitoBio/purell v1.1.1
 	github.com/PuerkitoBio/urlesc v0.0.0-20170810143723-de5bf2ad4578 // indirect
 	github.com/alecthomas/chroma v0.9.2
@@ -45,6 +44,7 @@ require (
 	github.com/niklasfasching/go-org v1.5.0
 	github.com/olekukonko/tablewriter v0.0.5
 	github.com/pelletier/go-toml v1.9.3
+	github.com/pelletier/go-toml/v2 v2.0.0-beta.3
 	github.com/pkg/errors v0.9.1
 	github.com/rogpeppe/go-internal v1.8.0
 	github.com/russross/blackfriday v1.5.3-0.20200218234912-41c5fccfd6f6

go.sum

@@ -433,6 +433,8 @@ github.com/olekukonko/tablewriter v0.0.5/go.mod h1:hPp6KlRPjbx+hW8ykQs1w3UBbZlj6
 github.com/pascaldekloe/goe v0.0.0-20180627143212-57f6aae5913c/go.mod h1:lzWF7FIEvWOWxwDKqyGYQf6ZUaNfKdP144TG7ZOy1lc=
 github.com/pelletier/go-toml v1.9.3 h1:zeC5b1GviRUyKYd6OJPvBU/mcVDVoL1OhT17FCt5dSQ=
 github.com/pelletier/go-toml v1.9.3/go.mod h1:u1nR/EPcESfeI/szUZKdtJ0xRNbUoANCkoOuaOx1Y+c=
+github.com/pelletier/go-toml/v2 v2.0.0-beta.3 h1:PNCTU4naEJ8mKal97P3A2qDU74QRQGlv4FXiL1XDqi4=
+github.com/pelletier/go-toml/v2 v2.0.0-beta.3/go.mod h1:aNseLYu/uKskg0zpr/kbr2z8yGuWtotWf/0BpGIAL2Y=
 github.com/pkg/diff v0.0.0-20210226163009-20ebb0f2a09e/go.mod h1:pJLUxLENpZxwdsKMEsNbx1VGcRFpLqf3715MtcvvzbA=
 github.com/pkg/errors v0.8.0/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
 github.com/pkg/errors v0.8.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
@@ -490,8 +492,9 @@ github.com/stretchr/testify v1.3.0/go.mod h1:M5WIy9Dh21IEIfnGCwXGc5bZfKNJtfHm1UV
 github.com/stretchr/testify v1.4.0/go.mod h1:j7eGeouHqKxXV5pUuKE4zz7dFj8WfuZ+81PSLYec5m4=
 github.com/stretchr/testify v1.5.1/go.mod h1:5W2xD1RspED5o8YsWQXVCued0rvSQ+mT+I5cxcmMvtA=
 github.com/stretchr/testify v1.6.1/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
-github.com/stretchr/testify v1.7.0 h1:nwc3DEeHmmLAfoZucVR881uASk0Mfjw8xYJ99tb5CcY=
 github.com/stretchr/testify v1.7.0/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
+github.com/stretchr/testify v1.7.1-0.20210427113832-6241f9ab9942 h1:t0lM6y/M5IiUZyvbBTcngso8SZEZICH7is9B6g/obVU=
+github.com/stretchr/testify v1.7.1-0.20210427113832-6241f9ab9942/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
 github.com/subosito/gotenv v1.2.0 h1:Slr1R9HxAlEKefgq5jn9U+DnETlIUa6HfgEzj0g5d7s=
 github.com/subosito/gotenv v1.2.0/go.mod h1:N0PQaV/YGNqwC0u51sEeR/aUtSLEXKX9iv69rRypqCw=
 github.com/tdewolff/minify/v2 v2.9.19 h1:QdCQhIqCeBnSWU/4e0nJ8QJeQUNO5CC7jrH3xwETkVI=

parser/frontmatter.go

@@ -20,7 +20,7 @@ import (
 
 	"github.com/gohugoio/hugo/parser/metadecoders"
 
-	"github.com/BurntSushi/toml"
+	toml "github.com/pelletier/go-toml/v2"
 
 	yaml "gopkg.in/yaml.v2"
 )

parser/frontmatter_test.go

@@ -31,9 +31,9 @@ func TestInterfaceToConfig(t *testing.T) {
 		// TOML
 		{map[string]interface{}{}, metadecoders.TOML, nil, false},
 		{
-			map[string]interface{}{"title": "test 1"},
+			map[string]interface{}{"title": "test' 1"},
 			metadecoders.TOML,
-			[]byte("title = \"test 1\"\n"),
+			[]byte("title = \"test' 1\"\n"),
 			false,
 		},
 

parser/metadecoders/decoder.go

@@ -24,7 +24,7 @@ import (
 	"github.com/gohugoio/hugo/common/herrors"
 	"github.com/niklasfasching/go-org/org"
 
-	"github.com/BurntSushi/toml"
+	toml "github.com/pelletier/go-toml/v2"
 	"github.com/pkg/errors"
 	"github.com/spf13/afero"
 	"github.com/spf13/cast"