Add readonly where applicable

Author: stevebauman

src/Calculation/Duration.php

@@ -4,7 +4,7 @@
 
 use Carbon\CarbonImmutable;
 
-class Duration
+readonly class Duration
 {
     public const EMPTY = [
         'day' => 0,

src/Calculation/MergingCalculation.php

@@ -7,7 +7,7 @@
 use Chrono\ParsedComponents;
 use Chrono\ParsedResult;
 
-class MergingCalculation
+readonly class MergingCalculation
 {
     /**
      * Merge date and time parsing results using upstream Chrono's merge semantics.

src/Calculation/Weekdays.php

@@ -7,7 +7,7 @@
 use Chrono\Reference;
 use Chrono\Weekday;
 
-class Weekdays
+readonly class Weekdays
 {
     /**
      * Create parsing components at the requested weekday.

src/Calculation/Years.php

@@ -4,7 +4,7 @@
 
 use Carbon\CarbonImmutable;
 
-class Years
+readonly class Years
 {
     /**
      * Find the most likely AD year from a raw number.

src/CasualReferences.php

@@ -2,7 +2,7 @@
 
 namespace Chrono;
 
-class CasualReferences
+readonly class CasualReferences
 {
     /**
      * Create components for the current reference moment.

src/Chrono.php

@@ -21,7 +21,7 @@
 use Chrono\Locales\Zh\ZhHansChrono;
 use Chrono\Locales\Zh\ZhHantChrono;
 
-class Chrono
+readonly class Chrono
 {
     /**
      * Create a Chrono facade around the given parsing engine.

src/Configuration.php

@@ -2,7 +2,7 @@
 
 namespace Chrono;
 
-class Configuration
+readonly class Configuration
 {
     /**
      * Create a parser/refiner configuration.

src/ConfiguredChronoEngine.php

@@ -2,7 +2,7 @@
 
 namespace Chrono;
 
-class ConfiguredChronoEngine implements ChronoEngine
+readonly class ConfiguredChronoEngine implements ChronoEngine
 {
     /**
      * Create a Chrono engine from the given configuration.

src/Dates.php

@@ -4,7 +4,7 @@
 
 use Carbon\CarbonImmutable;
 
-class Dates
+readonly class Dates
 {
     /**
      * Assign date components from a matching Carbon date.

src/Locales/De/DeChrono.php

@@ -26,7 +26,7 @@
 use Chrono\Refiners\OverlapRemovalRefiner;
 use Chrono\Refiners\UnlikelyFormatFilter;
 
-class DeChrono extends ConfiguredChronoEngine
+readonly class DeChrono extends ConfiguredChronoEngine
 {
     /**
      * Create a configured German Chrono engine.