ci: cancel overridden workflows (XRPLF#4597)

Small quality-of-life improvements to workflows using new concurrency
control features:

https://docs.github.com/en/actions/using-jobs/using-concurrency

At time of this commit, macOS runners are oversubscribed. This may help.

.github/workflows/doxygen.yml

@@ -4,6 +4,9 @@ on:
   push:
     branches:
       - develop
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
 
 jobs:
   job:
@@ -18,7 +21,7 @@ jobs:
           echo ${PATH} | tr ':' '\n'
           cmake --version
           doxygen --version
-          env
+          env | sort
       - name: build
         run: |
           mkdir build

.github/workflows/macos.yml

@@ -1,5 +1,8 @@
 name: macos
 on: [push, pull_request]
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
 
 jobs:
 
@@ -29,7 +32,7 @@ jobs:
           python --version
           conan --version
           cmake --version
-          env
+          env | sort
       - name: build
         uses: ./.github/actions/build
         with:

.github/workflows/nix.yml

@@ -1,5 +1,8 @@
 name: nix
 on: [push, pull_request]
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
 
 # This workflow has two job matrixes.
 # They can be considered phases because the second matrix ("test")
@@ -57,7 +60,7 @@ jobs:
           echo ${PATH} | tr ':' '\n'
           conan --version
           cmake --version
-          env
+          env | sort
       - name: configure Conan
         env:
           CONAN_URL: http://18.143.149.228:8081/artifactory/api/conan/conan-non-prod
@@ -139,7 +142,7 @@ jobs:
           echo ${PATH} | tr ':' '\n'
           conan --version
           cmake --version
-          env
+          env | sort
           ls ~/.conan
       - name: checkout
         uses: actions/checkout@v3