build: use 3.10.0-rc.1 (#1204)

Author: nedbat

.github/workflows/coverage.yml

@@ -34,7 +34,7 @@ jobs:
           - "3.7"
           - "3.8"
           - "3.9"
-          - "3.10.0-beta.4"
+          - "3.10.0-rc.1"
           - "pypy3"
         exclude:
           # Windows PyPy doesn't seem to work?

.github/workflows/kit.yml

@@ -127,7 +127,7 @@ jobs:
           - windows-latest
           - macos-latest
         python-version:
-          - "3.10.0-alpha.7"
+          - "3.10.0-rc.1"
       fail-fast: false
 
     steps:

.github/workflows/testsuite.yml

@@ -30,7 +30,7 @@ jobs:
           - "3.7"
           - "3.8"
           - "3.9"
-          - "3.10.0-beta.4"
+          - "3.10.0-rc.1"
           - "pypy3"
         exclude:
           # Windows PyPy doesn't seem to work?