Fix go sec findings

Add undefined variables for function calls where there results are not
used and are not required for the respective operation.

Author: HeavyWombat

parse.go

@@ -147,7 +147,7 @@ func parseSelectGraphicRenditionEscapeSequence(escapeSeq string) (uint64, error)
 func processTextAnnotations(text *String) error {
 	var buffer bytes.Buffer
 	for _, coloredRune := range *text {
-		buffer.WriteByte(byte(coloredRune.Symbol))
+		_ = buffer.WriteByte(byte(coloredRune.Symbol))
 	}
 
 	raw := buffer.String()

render.go

@@ -50,16 +50,16 @@ func (s String) String() string {
 				prepend = append(prepend, 0)
 			}
 
-			buffer.WriteString(renderSGR(coloredRune.Settings, prepend...))
+			_, _ = buffer.WriteString(renderSGR(coloredRune.Settings, prepend...))
 			current = coloredRune.Settings
 		}
 
-		buffer.WriteByte(byte(coloredRune.Symbol))
+		_ = buffer.WriteByte(byte(coloredRune.Symbol))
 	}
 
 	// Make sure to finish with a reset escape sequence
 	if current != 0 {
-		buffer.WriteString(renderSGR(0))
+		_, _ = buffer.WriteString(renderSGR(0))
 	}
 
 	return buffer.String()