Update schema-salad requirement from <8,>=7 to >=7,<9

Updates the requirements on [schema-salad](https://github.com/common-workflow-language/schema_salad) to permit the latest version.
- [Release notes](https://github.com/common-workflow-language/schema_salad/releases)
- [Commits](common-workflow-language/schema_salad@7.0.20200612160654...8.0.20210624154013)

---
updated-dependencies:
- dependency-name: schema-salad
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

requirements.txt

@@ -1,4 +1,4 @@
 requests
-schema-salad >= 7, < 8
+schema-salad >= 7, < 9
 typing_extensions
 cwltool

setup.py

@@ -19,7 +19,7 @@
     python_requires=">=3.6",
     install_requires=[
         "requests",
-        "schema-salad >= 7, < 8",
+        "schema-salad >= 7, < 9",
         "typing_extensions",
         "cwltool >= 3.0.20201113183607",
         "cwlformat",