gradle 7.x support

[rr-nick-tan]

hi folks
this is a nice plugin, but i got the error on my project with gradle 7.3.2 on Java 11

> Could not resolve all files for configuration ':classpath'.
   > Could not resolve ru.fix:gradle-release-plugin:1.4.3.
     Required by:
         project :
      > No matching variant of ru.fix:gradle-release-plugin:1.4.3 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 '7.3.2' but:
          - Variant 'apiElements' capability ru.fix:gradle-release-plugin:1.4.3 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 '7.3.2')
          - Variant 'runtimeElements' capability ru.fix:gradle-release-plugin:1.4.3 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 '7.3.2')

version info:

$ ./gradlew --version

------------------------------------------------------------
Gradle 7.3.2
------------------------------------------------------------

Build time:   2021-12-15 11:22:31 UTC
Revision:     26c186eb63b2b02e68d83b0dbc6ec69ab118653a

Kotlin:       1.5.31
Groovy:       3.0.9
Ant:          Apache Ant(TM) version 1.10.11 compiled on July 10 2021
JVM:          1.8.0_192 (Oracle Corporation 25.192-b12)
OS:           Mac OS X 10.16 x86_64