Docker build failure

[SpangleLabs]

Hey there, I cloned the repo and tried docker build . and got this exception:

spangle@kobold:~/prometheus-telegram-alert$ docker build .
Sending build context to Docker daemon  429.6kB
Step 1/10 : FROM openjdk:8-jdk-alpine AS builder
 ---> a3562aa0b991
Step 2/10 : WORKDIR /src
 ---> Using cache
 ---> 2b9b40b67005
Step 3/10 : COPY . .
 ---> 7a4d7a5d55d4
Step 4/10 : RUN chmod +x gradlew
 ---> Running in f3a8d593412f
Removing intermediate container f3a8d593412f
 ---> 75a5cc0a6fc0
Step 5/10 : RUN ./gradlew clean build
 ---> Running in e9734fd88ac9
Downloading https://services.gradle.org/distributions/gradle-5.5.1-all.zip
.............................................................................................................
.....................

Welcome to Gradle 5.5.1!

Here are the highlights of this release:
 - Kickstart Gradle plugin development with gradle init
 - Distribute organization-wide Gradle properties in custom Gradle distributions
 - Transform dependency artifacts on resolution

For more details see https://docs.gradle.org/5.5.1/release-notes.html

Starting a Gradle Daemon (subsequent builds will be faster)

FAILURE: Build failed with an exception.

* Where:
Build file '/src/build.gradle' line: 10

* What went wrong:
An exception occurred applying plugin request [id: 'org.springframework.boot', version: '2.4.4']
> Failed to apply plugin [id 'org.springframework.boot']
   > Spring Boot plugin requires Gradle 5 (5.6.x only) or Gradle 6 (6.3 or later). The current version is Gra
dle 5.5.1

* Try:
Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output
. Run with --scan to get full insights.

* Get more help at https://help.gradle.org

BUILD FAILED in 23s
The command '/bin/sh -c ./gradlew clean build' returned a non-zero code: 1