Fix deprecated flag casing for flags (#3201)

Lowercase the remaining deprecated flags to fix sentence structure.

private/buf/cmd/buf/command/generate/generate.go

@@ -460,7 +460,7 @@ func (f *flags) Bind(flagSet *pflag.FlagSet) {
 		nil,
 		"The types (package, message, enum, extension, service, method) that should be included in this image. When specified, the resulting image will only include descriptors to describe the requested types. Flag usage overrides buf.gen.yaml",
 	)
-	_ = flagSet.MarkDeprecated(typeDeprecatedFlagName, fmt.Sprintf("Use --%s instead", typeFlagName))
+	_ = flagSet.MarkDeprecated(typeDeprecatedFlagName, fmt.Sprintf("use --%s instead", typeFlagName))
 	_ = flagSet.MarkHidden(typeDeprecatedFlagName)
 }
 

private/buf/cmd/buf/command/lsfiles/lsfiles.go

@@ -138,15 +138,15 @@ func (f *flags) Bind(flagSet *pflag.FlagSet) {
 			stringutil.SliceToString(bufanalysis.AllFormatStrings),
 		),
 	)
-	_ = flagSet.MarkDeprecated(errorFormatFlagName, "This flag no longer has any effect")
+	_ = flagSet.MarkDeprecated(errorFormatFlagName, "this flag no longer has any effect")
 	_ = flagSet.MarkHidden(errorFormatFlagName)
 	flagSet.BoolVar(
 		&f.AsImportPaths,
 		asImportPathsFlagName,
 		false,
 		"Strip local directory paths and print filepaths as they are imported",
 	)
-	_ = flagSet.MarkDeprecated(asImportPathsFlagName, fmt.Sprintf("Use --%s=import instead", formatFlagName))
+	_ = flagSet.MarkDeprecated(asImportPathsFlagName, fmt.Sprintf("use --%s=import instead", formatFlagName))
 	_ = flagSet.MarkHidden(asImportPathsFlagName)
 }
 

private/buf/cmd/buf/command/push/push.go

@@ -59,7 +59,7 @@ const (
 )
 
 var (
-	useLabelInstead = fmt.Sprintf("Use --%s instead.", labelFlagName)
+	useLabelInstead = fmt.Sprintf("use --%s instead.", labelFlagName)
 )
 
 // NewCommand returns a new Command.