go: update most dependencies to the latest version

It's a lot of work for dependabot for our outdated deps, let's
help it by making one huge manual update.

Signed-off-by: Ondřej Budai <ondrej@budai.cz>

vendor/github.com/aymerick/douceur/css/stylesheet.go

@@ -0,0 +1,25 @@
+package css
+
+// Stylesheet represents a parsed stylesheet
+type Stylesheet struct {
+	Rules []*Rule
+}
+
+// NewStylesheet instanciate a new Stylesheet
+func NewStylesheet() *Stylesheet {
+	return &Stylesheet{}
+}
+
+// Returns string representation of the Stylesheet
+func (sheet *Stylesheet) String() string {
+	result := ""
+
+	for _, rule := range sheet.Rules {
+		if result != "" {
+			result += "\n"
+		}
+		result += rule.String()
+	}
+
+	return result
+}