Update Repo for `main` branch (#2608)

Switch from `master` to `main` for the default branch
* Update CircleCI configuration
* Update Gradle snapshot detection
* Update issue templates

Signed-off-by: Danno Ferrin <danno.ferrin@gmail.com>

.circleci/config.yml

@@ -294,7 +294,7 @@ workflows:
           filters:
             branches:
               only:
-                - master
+                - main
                 - /^release-.*/
           requires:
             - integrationTests
@@ -307,7 +307,7 @@ workflows:
           filters:
             branches:
               only:
-                - master
+                - main
                 - /^release-.*/
           requires:
             - integrationTests

.github/issue_template.md

@@ -1,7 +1,7 @@
 <!-- Have you done the following? -->
 <!--   * read the Code of Conduct? By filing an Issue, you are expected to -->  
 <!--     comply with it, including treating everyone with respect: -->
-<!--     https://github.com/hyperledger/besu/blob/master/CODE_OF_CONDUCT.md -->
+<!--     https://github.com/hyperledger/besu/blob/main/CODE_OF_CONDUCT.md -->
 <!--   * Reproduced the issue in the latest version of the software -->
 <!--   * Read the debugging docs: https://besu.hyperledger.org/en/stable/HowTo/Monitor/Logging/ -->
 <!--   * Duplicate Issue check:  https://github.com/search?q=+is%3Aissue+repo%3Ahyperledger/Besu -->

.github/pull_request_template.md

@@ -1,5 +1,5 @@
 <!-- Thanks for sending a pull request! Please check out our contribution guidelines: -->
-<!-- https://github.com/hyperledger/besu/blob/master/CONTRIBUTING.md -->
+<!-- https://github.com/hyperledger/besu/blob/main/CONTRIBUTING.md -->
 
 ## PR description
 

.github/workflows/repolinter.yml

@@ -21,4 +21,4 @@ jobs:
       - name: Checkout Code
         uses: actions/checkout@v2
       - name: Lint Repo
-        run: bundle exec /app/bin/repolinter.js --rulesetUrl https://raw.githubusercontent.com/hyperledger-labs/hyperledger-community-management-tools/master/repo_structure/repolint.json --format markdown
+        run: bundle exec /app/bin/repolinter.js --rulesetUrl https://raw.githubusercontent.com/hyperledger-labs/hyperledger-community-management-tools/main/repo_structure/repolint.json --format markdown

build.gradle

@@ -713,7 +713,7 @@ task dockerUpload {
   def image = "${imageName}:${dockerBuildVersion}"
   def additionalTags = []
 
-  if (project.hasProperty('branch') && project.property('branch') == 'master') {
+  if (project.hasProperty('branch') && project.property('branch') == 'main') {
     additionalTags.add('develop')
   }
 

ethereum/evmtool/build.gradle

@@ -120,7 +120,7 @@ task dockerUpload(type: Exec) {
   def cmd = "docker push '${image}'"
   def additionalTags = []
 
-  if (project.hasProperty('branch') && project.property('branch') == 'master') {
+  if (project.hasProperty('branch') && project.property('branch') == 'main') {
     additionalTags.add('develop')
   }