Add rate limiting fix

Since this workflow can run across mutliple repos simultaneously due to the schedule, we need to introduce some randomization so that we don't hit GH rate limits too often. 

In addition to that, we check for the rate limit explicitly and wait until it resets if we're nevertheless too close to it.

Author: kzu

.github/workflows/dotnet-file.yml

@@ -1,4 +1,4 @@
-# Synchronizes .netconfig-configured files with dotnet-file
+# Synchronizes .netconfig-configured files with dotnet-file
 name: dotnet-file
 on:
   workflow_dispatch:
@@ -22,6 +22,22 @@ jobs:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
         run: echo "GH_TOKEN=${GITHUB_TOKEN}" >> $GITHUB_ENV
 
+      - name: ⌛ rate
+        shell: pwsh
+        run: |
+          # add random sleep since we run on fixed schedule
+          sleep (get-random -max 60)
+          # get currently authenticated user rate limit info
+          $rate = gh api rate_limit | convertfrom-json | select -expandproperty rate
+          # if we don't have at least 100 requests left, wait until reset
+          if ($rate.remaining -lt 10) {
+              $wait = ($rate.reset - (Get-Date (Get-Date).ToUniversalTime() -UFormat %s))
+              echo "Rate limit remaining is $($rate.remaining), waiting for $($wait / 1000) seconds to reset"
+              sleep $wait
+              $rate = gh api rate_limit | convertfrom-json | select -expandproperty rate
+              echo "Rate limit has reset to $($rate.remaining) requests"
+          }
+
       - name: 🤘 checkout
         uses: actions/checkout@v2
         with:
@@ -30,6 +46,7 @@ jobs:
           token: ${{ env.GH_TOKEN }}
 
       - name: 🔄 sync
+        shell: pwsh
         run: |
           dotnet tool update -g dotnet-gcm
           dotnet gcm store --protocol=https --host=github.com --username=$env:GITHUB_ACTOR --password=$env:GH_TOKEN