Update macOS 10.14 to 10.15 (#80)

* Update macOS 10.14 to 10.15

* Update macOS 10.14 to 10.15

* Update macOS 10.14 to 10.15

Author: hugovk

.github/ISSUE_TEMPLATE/bug-report.md

@@ -11,7 +11,7 @@ assignees: ''
 A clear and concise description of what the bug is, and why you consider it to be a bug.
 
 **Virtual environments affected**
-- [ ] macOS 10.14
+- [ ] macOS 10.15
 - [ ] Ubuntu 16.04 LTS
 - [ ] Ubuntu 18.04 LTS
 - [ ] Windows Server 2016 R2

.github/ISSUE_TEMPLATE/tool-request.md

@@ -17,7 +17,7 @@ assignees: ''
   - URL for tool's homepage: <!--- URL -->
 
 **Virtual environments affected**
-- [ ] macOS 10.14
+- [ ] macOS 10.15
 - [ ] Ubuntu 16.04 LTS
 - [ ] Ubuntu 18.04 LTS
 - [ ] Windows Server 2016 R2
@@ -27,4 +27,4 @@ assignees: ''
 <!--- If so, please provide a description of how and approximately how much time it takes.  -->
 
 **Are you willing to submit a PR?**
-<!--- We accept contributions! -->
+<!--- We accept contributions! -->

README.md

@@ -10,7 +10,7 @@ check out the [GitHub Actions Community Forum](https://github.community/t5/GitHu
 We currently offer Linux, macOS, and Windows virtual environments:
 
 - **Linux**. We offer Ubuntu 16.04 and Ubuntu 18.04. We do not plan to offer other Linux distributions. If you want to build using other distributions with the hosted virtual environments, we suggest you use Docker. Alternatively, you can host your own VMs and make use of self-hosted runners which will be available when GitHub Actions becomes generally available on November 13, 2019. 
-- **macOS**. We offer macOS 10.14. We will update to macOS 10.15 before GitHub Actions becomes generally available on November 13, 2019.
+- **macOS**. We offer macOS Catalina 10.15.
 - **Windows**. We offer Windows Server 2016 and Windows Server 2019. However, we plan to offer only Windows Server 2019 starting on November 7, 2019. We plan to add Visual Studio 2017 to the Windows Server 2019 virtual environment, but do not yet have a firm ETA.
 
 ## Guidelines for what's installed