[light] Modernize namespace declarations to C++17 syntax (#11986)

esphome/components/light/esp_range_view.cpp

@@ -1,8 +1,7 @@
 #include "esp_range_view.h"
 #include "addressable_light.h"
 
-namespace esphome {
-namespace light {
+namespace esphome::light {
 
 int32_t HOT interpret_index(int32_t index, int32_t size) {
   if (index < 0)
@@ -92,5 +91,4 @@ ESPRangeView &ESPRangeView::operator=(const ESPRangeView &rhs) {  // NOLINT
 
 ESPColorView ESPRangeIterator::operator*() const { return this->range_.parent_->get(this->i_); }
 
-}  // namespace light
-}  // namespace esphome
+}  // namespace esphome::light