Fix Conda package workflows on PRs

Author: ndgrigorian

.github/workflows/build-docs.yml

@@ -1,4 +1,5 @@
 name: Build mkl_random documentation
+
 on:
   pull_request:
   push:

.github/workflows/conda-package-cf.yml

@@ -1,6 +1,9 @@
 name: Conda package using conda-forge
 
-on: push
+on:
+  pull_request:
+  push:
+    branches: [master]
 
 permissions: read-all
 

.github/workflows/conda-package.yml

@@ -1,6 +1,9 @@
 name: Conda package
 
-on: push
+on:
+  pull_request:
+  push:
+    branches: [master]
 
 permissions: read-all