When trying to build i get the following issue, and it looks like the security certificate expired on Mon Apr 26 16:05:42 MDT 2021 or Cardinal Components v2.5.0 does not exist. I believe that upgrading to Cardinal components 2.6.0 might work. Below is the error message outputed by IDEA.

Could not resolve all files for configuration ':modCompileClasspath'.
   > Could not resolve io.github.onyxstudios.Cardinal-Components-API:cardinal-components-base:2.5.0.
     Required by:
         project : > dev.emi:trinkets:2.6.7
      > Could not resolve io.github.onyxstudios.Cardinal-Components-API:cardinal-components-base:2.5.0.
         > Could not get resource 'https://maven.abusedmaster.xyz/io/github/onyxstudios/Cardinal-Components-API/cardinal-components-base/2.5.0/cardinal-components-base-2.5.0.pom'.
            > Could not GET 'https://maven.abusedmaster.xyz/io/github/onyxstudios/Cardinal-Components-API/cardinal-components-base/2.5.0/cardinal-components-base-2.5.0.pom'.
               > The server may not support the client's requested TLS protocol versions: (TLSv1.2, TLSv1.3). You may need to configure the client to allow other protocols to be used. See: https://docs.gradle.org/7.0/userguide/build_environment.html#gradle_system_properties
                  > PKIX path validation failed: java.security.cert.CertPathValidatorException: validity check failed

When checking the maven in your browser, you will probably realize that 2.5.0 is indeed gone from the developers Maven.

Instead, the developer of Cardinal suggests in this wikipage to use "Ladesnakes Bintray" for 2.3.5 up to 2.7.11.
However, Bintray is now gone and suggest migration towards JFrog. Ladysnake owns JFrog as well, but didn't bother migrating the old versions to it just yet (or maybe can't because non-paid accounts can no longer login into Bintray).

Pullrequest #71 already includes an update of the dependancies that cause the problem (i can assume that "CCA entity" will have similiar issues). For the meantime, you can follow the suggestion in #85 and drop a modern version of CCA into your mods folder.

Looking into the build.gradle shows that Emi was probably aware of the issue with CCA, but forgot to update the README with the new repository. But now that Bintray is gone, that shouldn't matter anymore.

Edit: Apparently i am blind and didn't notice that the same wiki page includes an information on how to use jitpack to get CCA dependancies. This is identical with what Emi wrote on the README except the code for the build.gradle wasn't updated.

I am probably missing something but i don't understand how to compile my mod, gradle says that it cant resolve the CCA dependancy

I am probably missing something but i don't understand how to compile my mod, gradle says that it cant resolve the CCA dependancy

Add a Maven repository that includes the CCA Version you are looking for, then implement and include CCA as dependancy.
I currently use 2.8.3 for that and get it from Ladysnake newest maven:

repositories {
    [...]

    maven {
        name = "Ladysnake Mods"
        url = 'https://ladysnake.jfrog.io/artifactory/mods'
    }
}

dependencies {
    [...]

    modImplementation "io.github.onyxstudios.Cardinal-Components-API:cardinal-components-base:2.8.3"
    include "io.github.onyxstudios.Cardinal-Components-API:cardinal-components-base:2.8.3"
    modImplementation "io.github.onyxstudios.Cardinal-Components-API:cardinal-components-entity:2.8.3"
    include "io.github.onyxstudios.Cardinal-Components-API:cardinal-components-entity:2.8.3"
}

That is atleast what i am using for 1.16.5 testing for now. However, i currently paused and wait for the trinket recode of 1.17 to finish.