build: modernize Go usage

This commit modernizes Go usage. This was done with:

go run golang.org/x/tools/gopls/internal/analysis/modernize/cmd/modernize@latest -fix -test ./...

Then files needed to be `go fmt`ed and a few comments needed to be
restored.

The modernizations include replacing

- if/else conditional assignment by a call to the built-in min or max functions added in go1.21
- sort.Slice(x, func(i, j int) bool) { return s[i] < s[j] } by a call to slices.Sort(s), added in go1.21
- interface{} by the 'any' type added in go1.18
- append([]T(nil), s...) by slices.Clone(s) or slices.Concat(s), added in go1.21
- loop around an m[k]=v map update by a call to one of the Collect, Copy, Clone, or Insert functions from the maps package, added in go1.21
- []byte(fmt.Sprintf...) by fmt.Appendf(nil, ...), added in go1.19
- append(s[:i], s[i+1]...) by slices.Delete(s, i, i+1), added in go1.21
- a 3-clause for i := 0; i < n; i++ {} loop by for i := range n {}, added in go1.22

backend/box/box.go

@@ -237,8 +237,8 @@ func getClaims(boxConfig *api.ConfigJSON, boxSubType string) (claims *boxCustomC
 	return claims, nil
 }
 
-func getSigningHeaders(boxConfig *api.ConfigJSON) map[string]interface{} {
-	signingHeaders := map[string]interface{}{
+func getSigningHeaders(boxConfig *api.ConfigJSON) map[string]any {
+	signingHeaders := map[string]any{
 		"kid": boxConfig.BoxAppSettings.AppAuth.PublicKeyID,
 	}
 	return signingHeaders
@@ -1343,12 +1343,8 @@ func (f *Fs) changeNotifyRunner(ctx context.Context, notifyFunc func(string, fs.
 	nextStreamPosition = streamPosition
 
 	for {
-		limit := f.opt.ListChunk
-
 		// box only allows a max of 500 events
-		if limit > 500 {
-			limit = 500
-		}
+		limit := min(f.opt.ListChunk, 500)
 
 		opts := rest.Opts{
 			Method:     "GET",