Update to Maven 3.8.4 on OSX CI builds

Author: TheBlueMatt

.github/workflows/build.yml

@@ -290,15 +290,18 @@ jobs:
             ./genbindings.sh ./ldk-c-bindings/ "-I$JAVA_HOME/include/ -I$JAVA_HOME/include/darwin -isysroot$(xcrun --show-sdk-path)" false false || echo
             cat src/main/resources/liblightningjni_MacOSX-aarch64.nativelib > /dev/null
           fi
-      - name: Fetch Maven 3.8.3
+      - name: Fetch Maven 3.8.4
         run: |
-          wget -O apache-maven-3.8.3-bin.tar.gz https://apache.osuosl.org/maven/maven-3/3.8.3/binaries/apache-maven-3.8.3-bin.tar.gz
-          if [ "$(shasum -a 256 apache-maven-3.8.3-bin.tar.gz | awk '{ print $1 }')" != "0f1597d11085b8fe93d84652a18c6deea71ece9fabba45a02cf6600c7758fd5b" ]; then
+          # We don't bother using the upstream mirrors as they remove prior
+          # releases aggressively, causing spurious CI failures when we don't
+          # care about the version used.
+          wget -O apache-maven-3.8.4-bin.tar.gz https://bitcoin.ninja/apache-maven-3.8.4-bin.tar.gz
+          if [ "$(shasum -a 256 apache-maven-3.8.4-bin.tar.gz | awk '{ print $1 }')" != "2cdc9c519427bb20fdc25bef5a9063b790e4abd930e7b14b4e9f4863d6f9f13c" ]; then
             echo "Bad hash"
             exit 1
           fi
-          tar xvvf apache-maven-3.8.3-bin.tar.gz
-          export PATH=apache-maven-3.8.3/bin:$PATH
+          tar xvvf apache-maven-3.8.4-bin.tar.gz
+          export PATH=apache-maven-3.8.4/bin:$PATH
       - name: Run Java Tests against built jar
         run: |
           mvn -DskipTests=true package