fix: update gradle to 7.6.3

[meotch]

Summary of Changes

Resolves build issue w/ Gradle in subsequent projects

> Could not resolve all files for configuration ':classpath'.
   > Could not resolve com.github.mxenabled.coppuccino:coppuccino:4.4.1.
     Required by:
         project : > com.github.mxenabled.coppuccino:com.github.mxenabled.coppuccino.gradle.plugin:4.4.1
      > No matching variant of com.github.mxenabled.coppuccino:coppuccino:4.4.1 was found. The consumer was configured to find a runtime of a library compatible with Java 8, packaged as a jar, and its dependencies declared externally, as well as attribute 'org.gradle.plugin.api-version' with value '7.6.3' but:
          - Variant 'apiElements' capability com.github.mxenabled.coppuccino:coppuccino:4.4.1 declares a library, packaged as a jar, and its dependencies declared externally:
              - Incompatible because this component declares an API of a component compatible with Java 11 and the consumer needed a runtime of a component compatible with Java 8
              - Other compatible attribute:
                  - Doesn't say anything about org.gradle.plugin.api-version (required '7.6.3')
          - Variant 'runtimeElements' capability com.github.mxenabled.coppuccino:coppuccino:4.4.1 declares a runtime of a library, packaged as a jar, and its dependencies declared externally:
              - Incompatible because this component declares a component compatible with Java 11 and the consumer needed a component compatible with Java 8
              - Other compatible attribute:
                  - Doesn't say anything about org.gradle.plugin.api-version (required '7.6.3')
                  ```