chore(build): specify python binary for notary-client on UNIX explicitly (#1184)

Author: addaleax

packages/build/src/packaging/notary-service.spec.ts

@@ -57,7 +57,7 @@ describe('packaging artifact signing', () => {
         .find((arg: string) => arg.includes('notary-mongosh-token'));
 
       expect(spawnSync).to.have.been.calledWith(
-        'python',
+        process.platform === 'win32' ? 'python' : '/usr/bin/python',
         [
           process.platform === 'win32' ?
             'C:\\cygwin\\usr\\local\\bin\\notary-client.py' :

packages/build/src/packaging/notary-service.ts

@@ -8,7 +8,7 @@ const DEFAULT_OPTIONS: Partial<NotarizeOptions> = {
   clientPath: process.platform === 'win32' ?
     'C:\\cygwin\\usr\\local\\bin\\notary-client.py' :
     '/usr/local/bin/notary-client.py',
-  pythonExecutable: 'python'
+  pythonExecutable: process.platform === 'win32' ? 'python' : '/usr/bin/python'
 };
 
 export interface NotarizeOptions {