Upgrade Gradle including plugins

Upgrade Gradle to 7.3.3
Upgrade Shadow to 7.1.2
Upgrade Spotbugs to 4.5.3 (Gradle Plugin 5.0.4)

theodolite-benchmarks/buildSrc/build.gradle

-buildscript {
-  repositories {
-    maven {
-      url "https://plugins.gradle.org/m2/"
-    }
-  }
-  dependencies {
-    classpath "com.github.jengelman.gradle.plugins:shadow:6.0.0"
-  }
-}
-
 // to discover the precompiled script plugins
 plugins {
     id 'groovy-gradle-plugin'
@@ -19,6 +8,6 @@ repositories {
 }
 
 dependencies {
-    implementation 'gradle.plugin.com.github.spotbugs.snom:spotbugs-gradle-plugin:4.6.0'
-    implementation 'com.github.jengelman.gradle.plugins:shadow:6.0.0'
+    implementation 'com.github.spotbugs.snom:spotbugs-gradle-plugin:5.0.4'
+    implementation 'gradle.plugin.com.github.johnrengelman:shadow:7.1.2'
 }

theodolite-benchmarks/buildSrc/src/main/groovy/theodolite.java-conventions.gradle

@@ -66,5 +66,5 @@ spotbugs {
   reportLevel = "low"
   effort = "max"
   ignoreFailures = false
-  toolVersion = '4.1.4'
+  toolVersion = '4.5.3'
 }

theodolite-benchmarks/gradle/wrapper/gradle-wrapper.properties

 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-6.8.3-bin.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-7.3.3-bin.zip
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists